RFC 2911
This document is obsolete. Please refer to RFC 8011.






Network Working Group                                T. Hastings, Editor
Request for Comments: 2911                                    R. Herriot
Obsoletes: 2566                                        Xerox Corporation
Category: Standards Track                                       R. deBry
                                               Utah Valley State College
                                                             S. Isaacson
                                                            Novell, Inc.
                                                               P. Powell
                                                     Astart Technologies
                                                          September 2000


          Internet Printing Protocol/1.1: Model and Semantics

Status of this Memo



   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice



   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract



   This document is one of a set of documents, which together describe
   all aspects of a new Internet Printing Protocol (IPP).  IPP is an
   application level protocol that can be used for distributed printing
   using Internet tools and technologies.  This document describes a
   simplified model consisting of abstract objects, their attributes,
   and their operations that is independent of encoding and transport.
   The model consists of a Printer and a Job object.  A Job optionally
   supports multiple documents.  IPP 1.1 semantics allow end-users and
   operators to query printer capabilities, submit print jobs, inquire
   about the status of print jobs and printers, cancel, hold, release,
   and restart print jobs.  IPP 1.1 semantics allow operators to pause,
   resume, and purge (jobs from) Printer objects.  This document also
   addresses security, internationalization, and directory issues.










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RFC 2911              IPP/1.1: Model and Semantics        September 2000


   The full set of IPP documents includes:

     Design Goals for an Internet Printing Protocol [RFC2567]
     Rationale for the Structure and Model and Protocol for the Internet
     Printing Protocol [RFC2568]
     Internet Printing Protocol/1.1: Model and Semantics (this document)
     Internet Printing Protocol/1.1: Encoding and Transport [RFC2910]
     Internet Printing Protocol/1.1: Implementer's Guide [IPP-IIG]
     Mapping between LPD and IPP Protocols [RFC2569]

   The "Design Goals for an Internet Printing Protocol" document takes a
   broad look at distributed printing functionality, and it enumerates
   real-life scenarios that help to clarify the features that need to be
   included in a printing protocol for the Internet.  It identifies
   requirements for three types of users: end users, operators, and
   administrators.  It calls out a subset of end user requirements that
   are satisfied in IPP/1.0.  A few OPTIONAL operator operations have
   been added to IPP/1.1.

   The "Rationale for the Structure and Model and Protocol for the
   Internet Printing Protocol" document describes IPP from a high level
   view, defines a roadmap for the various documents that form the suite
   of IPP specification documents, and gives background and rationale
   for the IETF working group's major decisions.

   The "Internet Printing Protocol/1.1: Encoding and Transport" document
   is a formal mapping of the abstract operations and attributes defined
   in the model document onto HTTP/1.1 [RFC2616].  It defines the
   encoding rules for a new Internet MIME media type called
   "application/ipp".  This document also defines the rules for
   transporting over HTTP a message body whose Content-Type is
   "application/ipp".  This document defines a new scheme named 'ipp'
   for identifying IPP printers and jobs.

   The "Internet Printing Protocol/1.1: Implementer's Guide" document
   gives insight and advice to implementers of IPP clients and IPP
   objects.  It is intended to help them understand IPP/1.1 and some of
   the considerations that may assist them in the design of their client
   and/or IPP object implementations.  For example, a typical order of
   processing requests is given, including error checking.  Motivation
   for some of the specification decisions is also included.

   The "Mapping between LPD and IPP Protocols" document gives some
   advice to implementers of gateways between IPP and LPD (Line Printer
   Daemon) implementations.






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RFC 2911              IPP/1.1: Model and Semantics        September 2000


Table of Contents



   1.   Introduction                                                 9
   1.1   Simplified Printing Model                                  10
   2.   IPP Objects                                                 12
   2.1   Printer Object                                             13
   2.2   Job Object                                                 15
   2.3   Object Relationships                                       16
   2.4   Object Identity                                            17
   3.   IPP Operations                                              20
   3.1   Common Semantics                                           21
   3.1.1  Required Parameters                                       21
   3.1.2  Operation IDs and Request IDs                             22
   3.1.3  Attributes                                                22
   3.1.4  Character Set and Natural Language Operation Attribute    24
   3.1.4.1   Request Operation Attributes                           25
   3.1.4.2   Response Operation Attributes                          29
   3.1.5  Operation Targets                                         30
   3.1.6  Operation Response Status Codes and Status Messages       32
   3.1.6.1   "status-code" (type2 enum)                             32
   3.1.6.2   "status-message" (text(255))                           33
   3.1.6.3   "detailed-status-message" (text(MAX))                  33
   3.1.6.4   "document-access-error" (text(MAX))                    34
   3.1.7  Unsupported Attributes                                    34
   3.1.8  Versions                                                  36
   3.1.9  Job Creation Operations                                   38
   3.2   Printer Operations                                         41
   3.2.1  Print-Job Operation                                       41
   3.2.1.1   Print-Job Request                                      41
   3.2.1.2   Print-Job Response                                     46
   3.2.2  Print-URI Operation                                       48
   3.2.3  Validate-Job Operation                                    49
   3.2.4  Create-Job Operation                                      49
   3.2.5  Get-Printer-Attributes Operation                          50
   3.2.5.1   Get-Printer-Attributes Request                         51
   3.2.5.2   Get-Printer-Attributes Response                        53
   3.2.6  Get-Jobs Operation                                        54
   3.2.6.1   Get-Jobs Request                                       54
   3.2.6.2   Get-Jobs Response                                      56
   3.2.7  Pause-Printer Operation                                   57
   3.2.7.1   Pause-Printer Request                                  59
   3.2.7.2   Pause-Printer Response                                 60
   3.2.8  Resume-Printer Operation                                  60
   3.2.9  Purge-Jobs Operation                                      61
   3.3   Job Operations                                             62
   3.3.1  Send-Document Operation                                   62
   3.3.1.1   Send-Document Request                                  64
   3.3.1.2   Send-Document Response                                 65



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RFC 2911              IPP/1.1: Model and Semantics        September 2000


   3.3.2  Send-URI Operation                                        66
   3.3.3  Cancel-Job Operation                                      66
   3.3.3.1   Cancel-Job Request                                     67
   3.3.3.2   Cancel-Job Response                                    68
   3.3.4  Get-Job-Attributes Operation                              69
   3.3.4.1   Get-Job-Attributes Request                             69
   3.3.4.2   Get-Job-Attributes Response                            70
   3.3.5  Hold-Job Operation                                        71
   3.3.5.1   Hold-Job Request                                       72
   3.3.5.2   Hold-Job Response                                      73
   3.3.6  Release-Job Operation                                     74
   3.3.7  Restart-Job Operation                                     75
   3.3.7.1   Restart-Job Request                                    76
   3.3.7.2   Restart-Job Response                                   78
   4.   Object Attributes                                           78
   4.1   Attribute Syntaxes                                         78
   4.1.1  'text'                                                    79
   4.1.1.1   'textWithoutLanguage'                                  80
   4.1.1.2   'textWithLanguage'                                     80
   4.1.2  'name'                                                    81
   4.1.2.1   'nameWithoutLanguage'                                  82
   4.1.2.2   'nameWithLanguage'                                     82
   4.1.2.3   Matching 'name' attribute values                       83
   4.1.3  'keyword'                                                 84
   4.1.4  'enum'                                                    85
   4.1.5  'uri'                                                     85
   4.1.6  'uriScheme'                                               86
   4.1.7  'charset'                                                 86
   4.1.8  'naturalLanguage'                                         87
   4.1.9  'mimeMediaType'                                           87
   4.1.9.1 Application/octet-stream -- Auto-Sensing                 88
           the document format
   4.1.10 'octetString'                                             89
   4.1.11 'boolean'                                                 89
   4.1.12 'integer'                                                 89
   4.1.13 'rangeOfInteger'                                          90
   4.1.14 'dateTime'                                                90
   4.1.15 'resolution'                                              90
   4.1.16 '1setOf  X'                                               90
   4.2   Job Template Attributes                                    91
   4.2.1  job-priority (integer(1:100))                             94
   4.2.2  job-hold-until (type3 keyword | name (MAX))               95
   4.2.3  job-sheets (type3 keyword | name(MAX))                    96
   4.2.4  multiple-document-handling (type2 keyword)                96
   4.2.5  copies (integer(1:MAX))                                   98
   4.2.6  finishings (1setOf type2 enum)                            98
   4.2.7  page-ranges (1setOf rangeOfInteger (1:MAX))              101
   4.2.8  sides (type2 keyword)                                    102



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RFC 2911              IPP/1.1: Model and Semantics        September 2000


   4.2.9  number-up (integer(1:MAX))                               102
   4.2.10 orientation-requested (type2 enum)                       103
   4.2.11 media (type3 keyword | name(MAX))                        104
   4.2.12 printer-resolution (resolution)                          105
   4.2.13 print-quality (type2 enum)                               105
   4.3   Job Description Attributes                                106
   4.3.1  job-uri (uri)                                            107
   4.3.2  job-id (integer(1:MAX))                                  108
   4.3.3  job-printer-uri (uri)                                    108
   4.3.4  job-more-info (uri)                                      108
   4.3.5  job-name (name(MAX))                                     108
   4.3.6  job-originating-user-name (name(MAX))                    109
   4.3.7  job-state (type1 enum)                                   109
   4.3.7.1   Forwarding Servers                                    112
   4.3.7.2   Partitioning of Job States                            112
   4.3.8  job-state-reasons (1setOf  type2 keyword)                113
   4.3.9  job-state-message (text(MAX))                            118
   4.3.10 job-detailed-status-messages (1setOf text(MAX))          118
   4.3.11 job-document-access-errors (1setOf text(MAX))            118
   4.3.12 number-of-documents (integer(0:MAX))                     119
   4.3.13 output-device-assigned (name(127))                       119
   4.3.14 Event Time Job Description Attributes                    119
   4.3.14.1  time-at-creation (integer(MIN:MAX))                   120
   4.3.14.2  time-at-processing (integer(MIN:MAX))                 120
   4.3.14.3  time-at-completed (integer(MIN:MAX))                  120
   4.3.14.4  job-printer-up-time (integer(1:MAX))                  120
   4.3.14.5  date-time-at-creation (dateTime)                      121
   4.3.14.6  date-time-at-processing (dateTime)                    121
   4.3.14.7  date-time-at-completed (dateTime)                     121
   4.3.15 number-of-intervening-jobs (integer(0:MAX))              121
   4.3.16 job-message-from-operator (text(127))                    121
   4.3.17 Job Size Attributes                                      121
   4.3.17.1  job-k-octets (integer(0:MAX))                         122
   4.3.17.2  job-impressions (integer(0:MAX))                      122
   4.3.17.3  job-media-sheets (integer(0:MAX))                     123
   4.3.18 Job Progress Attributes                                  123
   4.3.18.1  job-k-octets-processed (integer(0:MAX))               123
   4.3.18.2  job-impressions-completed (integer(0:MAX))            123
   4.3.18.3  job-media-sheets-completed (integer(0:MAX))           124
   4.3.19 attributes-charset (charset)                             124
   4.3.20 attributes-natural-language (naturalLanguage)            124
   4.4   Printer Description Attributes                            124
   4.4.1  printer-uri-supported (1setOf uri)                       126
   4.4.2  uri-authentication-supported (1setOf type2 keyword)      127
   4.4.3  uri-security-supported (1setOf type2 keyword)            128
   4.4.4  printer-name (name(127))                                 129
   4.4.5  printer-location (text(127))                             129
   4.4.6  printer-info (text(127))                                 130



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RFC 2911              IPP/1.1: Model and Semantics        September 2000


   4.4.7  printer-more-info (uri)                                  130
   4.4.8  printer-driver-installer (uri)                           130
   4.4.9  printer-make-and-model (text(127))                       130
   4.4.10 printer-more-info-manufacturer (uri)                     130
   4.4.11 printer-state (type1 enum)                               131
   4.4.12 printer-state-reasons (1setOf type2 keyword)             131
   4.4.13 printer-state-message (text(MAX))                        134
   4.4.14 ipp-versions-supported (1setOf type2 keyword)            134
   4.4.15 operations-supported (1setOf type2 enum)                 135
   4.4.16 multiple-document-jobs-supported (boolean)               136
   4.4.17 charset-configured (charset)                             136
   4.4.18 charset-supported (1setOf charset)                       137
   4.4.19 natural-language-configured (naturalLanguage)            137
   4.4.20 generated-natural-language-supported
          (1setOf naturalLanguage)                                 137
   4.4.21 document-format-default (mimeMediaType)                  138
   4.4.22 document-format-supported (1setOf mimeMediaType)         138
   4.4.23 printer-is-accepting-jobs (boolean)                      138
   4.4.24 queued-job-count (integer(0:MAX))                        138
   4.4.25 printer-message-from-operator (text(127))                139
   4.4.26 color-supported (boolean)                                139
   4.4.27 reference-uri-schemes-supported (1setOf uriScheme)       139
   4.4.28 pdl-override-supported (type2 keyword)                   139
   4.4.29 printer-up-time (integer(1:MAX))                         140
   4.4.30 printer-current-time (dateTime)                          140
   4.4.31 multiple-operation-time-out (integer(1:MAX))             141
   4.4.32 compression-supported (1setOf type3 keyword)             141
   4.4.33 job-k-octets-supported (rangeOfInteger(0:MAX))           142
   4.4.34 job-impressions-supported (rangeOfInteger(0:MAX))        142
   4.4.35 job-media-sheets-supported (rangeOfInteger(0:MAX))       142
   4.4.36 pages-per-minute (integer(0:MAX))                        142
   4.4.37 pages-per-minute-color (integer(0:MAX))                  142
   5.   Conformance                                                143
   5.1   Client Conformance Requirements                           143
   5.2   IPP Object Conformance Requirements                       145
   5.2.1  Objects                                                  145
   5.2.2  Operations                                               145
   5.2.3  IPP Object Attributes                                    146
   5.2.4  Versions                                                 146
   5.2.5  Extensions                                               147
   5.2.6  Attribute Syntaxes                                       147
   5.2.7  Security                                                 148
   5.3   Charset and Natural Language Requirements                 148
   6.   IANA Considerations                                        148
   6.1   Typed 'keyword' and 'enum' Extensions                     149
   6.2   Attribute Extensibility                                   151
   6.3   Attribute Syntax Extensibility                            152
   6.4   Operation Extensibility                                   152



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RFC 2911              IPP/1.1: Model and Semantics        September 2000


   6.5   Attribute Group Extensibility                             153
   6.6   Status Code Extensibility                                 153
   6.7   Out-of-band Attribute Value Extensibility                 154
   6.8   Registration of MIME types/sub-types for document-formats 154
   6.9   Registration of charsets for use in 'charset'
         attribute values                                          154
   7.   Internationalization Considerations                        154
   8.   Security Considerations                                    158
   8.1   Security Scenarios                                        159
   8.1.1  Client and Server in the Same Security Domain            159
   8.1.2  Client and Server in Different Security Domains          159
   8.1.3  Print by Reference                                       160
   8.2   URIs in Operation, Job, and Printer attributes            160
   8.3   URIs for each authentication mechanisms                   160
   8.4   Restricted Queries                                        161
   8.5   Operations performed by operators and system
         administrators                                            161
   8.6   Queries on jobs submitted using non-IPP protocols         162
   9.   References                                                 162
   10.  Authors' Addresses                                         166
   11.  Formats for IPP Registration Proposals                     168
   11.1  Type2 keyword attribute values registration               169
   11.2  Type3 keyword attribute values registration               169
   11.3  Type2 enum attribute values registration                  169
   11.4  Type3 enum attribute values registration                  170
   11.5  Attribute registration                                    170
   11.6  Attribute Syntax registration                             171
   11.7  Operation registration                                    171
   11.8  Attribute Group registration                              171
   11.9  Status code registration                                  172
   11.10 Out-of-band Attribute Value registration                  172
   12.  APPENDIX A: Terminology                                    173
   12.1  Conformance Terminology                                   173
   12.1.1 NEED NOT                                                 173
   12.2  Model Terminology                                         173
   12.2.1 Keyword                                                  173
   12.2.2 Attributes                                               173
   12.2.2.1  Attribute Name                                        173
   12.2.2.2  Attribute Group Name                                  174
   12.2.2.3  Attribute Value                                       174
   12.2.2.4  Attribute Syntax                                      174
   12.2.3 Supports                                                 174
   12.2.4 print-stream page                                        176
   12.2.5 impression                                               177
   13. APPENDIX B: Status Codes and Suggested Status Code Messages 177
   13.1  Status Codes                                              178
   13.1.1 Informational                                            178
   13.1.2 Successful Status Codes                                  178



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   13.1.2.1  successful-ok (0x0000)                                178
   13.1.2.2  successful-ok-ignored-or-substituted-attributes
             (0x0001)                                              179
   13.1.2.3  successful-ok-conflicting-attributes (0x0002)         179
   13.1.3 Redirection Status Codes                                 179
   13.1.4 Client Error Status Codes                                179
   13.1.4.1  client-error-bad-request (0x0400)                     180
   13.1.4.2  client-error-forbidden (0x0401)                       180
   13.1.4.3  client-error-not-authenticated (0x0402)               180
   13.1.4.4  client-error-not-authorized (0x0403)                  180
   13.1.4.5  client-error-not-possible (0x0404)                    180
   13.1.4.6  client-error-timeout (0x0405)                         181
   13.1.4.7  client-error-not-found (0x0406)                       181
   13.1.4.8  client-error-gone (0x0407)                            181
   13.1.4.9  client-error-request-entity-too-large (0x0408)        182
   13.1.4.10 client-error-request-value-too-long (0x0409)          182
   13.1.4.11 client-error-document-format-not-supported (0x040A)   182
   13.1.4.12 client-error-attributes-or-values-not-supported
             (0x040B)                                              183
   13.1.4.13 client-error-uri-scheme-not-supported (0x040C)        183
   13.1.4.14 client-error-charset-not-supported (0x040D)           183
   13.1.4.15 client-error-conflicting-attributes (0x040E)          183
   13.1.4.16 client-error-compression-not-supported (0x040F)       184
   13.1.4.17 client-error-compression-error (0x0410)               184
   13.1.4.18 client-error-document-format-error (0x0411)           184
   13.1.4.19 client-error-document-access-error (0x0412)           184
   13.1.5    Server Error Status Codes                             185
   13.1.5.1  server-error-internal-error (0x0500)                  185
   13.1.5.2  server-error-operation-not-supported (0x0501)         185
   13.1.5.3  server-error-service-unavailable (0x0502)             185
   13.1.5.4  server-error-version-not-supported (0x0503)           185
   13.1.5.5  server-error-device-error (0x0504)                    186
   13.1.5.6  server-error-temporary-error (0x0505)                 186
   13.1.5.7  server-error-not-accepting-jobs (0x0506)              187
   13.1.5.8  server-error-busy (0x0507)                            187
   13.1.5.9  server-error-job-canceled (0x0508)                    187
   13.1.5.10 server-error-multiple-document-jobs-not-supported
             (0x0509)                                              187
   13.2  Status Codes for IPP Operations                           187
   14.  APPENDIX C:  "media" keyword values                        190
   15.  APPENDIX D: Processing IPP Attributes                      208
   15.1  Fidelity                                                  209
   15.2  Page Description Language (PDL) Override                  210
   15.3  Using Job Template Attributes During Document Processing  212
   16.  APPENDIX E: Generic Directory Schema                       214
   17.  APPENDIX F:  Differences between the IPP/1.0 and IPP/1.1
        "Model and Semantics" Documents                            215
   18.  Full Copyright Statement                                   224



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RFC 2911              IPP/1.1: Model and Semantics        September 2000


1. Introduction



   The Internet Printing Protocol (IPP) is an application level protocol
   that can be used for distributed printing using Internet tools and
   technologies.  IPP version 1.1 (IPP/1.1) focuses primarily on end
   user functionality with a few administrative operations included.
   This document is just one of a suite of documents that fully define
   IPP.  The full set of IPP documents includes:

     Design Goals for an Internet Printing Protocol [RFC2567]
     Rationale for the Structure and Model and Protocol for the Internet
     Printing Protocol [RFC2568]
     Internet Printing Protocol/1.1: Model and Semantics (this document)
     Internet Printing Protocol/1.1: Encoding and Transport [RFC2910]
     Internet Printing Protocol/1.1: Implementer's Guide [IPP-IIG]
     Mapping between LPD and IPP Protocols [RFC2569]

   Anyone reading these documents for the first time is strongly
   encouraged to read the IPP documents in the above order.

   This document is laid out as follows:

   - The rest of Section 1 is an introduction to the IPP simplified
     model for distributed printing.
   - Section 2 introduces the object types covered in the model with
     their basic behaviors, attributes, and interactions.
   - Section 3 defines the operations included in IPP/1.1.  IPP
     operations are synchronous, therefore, for each operation, there is
     a both request and a response.
   - Section 4 defines the attributes (and their syntaxes) that are used
     in the model.
   - Sections 5 - 6 summarizes the implementation conformance
     requirements for objects that support the protocol and IANA
     considerations, respectively.
   - Sections 7 - 11 cover the Internationalization and Security
     considerations as well as References, Author contact information,
     and Formats for Registration Proposals.
   - Sections 12 - 14 are appendices that cover Terminology, Status
     Codes and Messages, and "media" keyword values.

       Note: This document uses terms such as "attributes", "keywords",
       and "support".  These terms have special meaning and are defined
       in the model terminology section 12.2.  Capitalized terms, such
       as MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, MAY, NEED NOT,
       and OPTIONAL, have special meaning relating to conformance.
       These terms are defined in section 12.1 on conformance
       terminology, most of which is taken from RFC 2119 [RFC2119].




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RFC 2911              IPP/1.1: Model and Semantics        September 2000


   - Section 15 is an appendix that helps to clarify the effects of
     interactions between related attributes and their values.
   - Section 16 is an appendix that enumerates the subset of Printer
     attributes that form a generic directory schema.  These attributes
     are useful when registering a Printer so that a client can find the
     Printer not just by name, but by filtered searches as well.
   - Section 17 is an appendix summarizing the additions and changes
     from the IPP/1.0 "Model and Semantics" document [RFC2566] to make
     this IPP/1.1 document.
   - Section 18 is the full copyright notice.

1.1 Simplified Printing Model



   In order to achieve its goal of realizing a workable printing
   protocol for the Internet, the Internet Printing Protocol (IPP) is
   based on a simplified printing model that abstracts the many
   components of real world printing solutions.  The Internet is a
   distributed computing environment where requesters of print services
   (clients, applications, printer drivers, etc.) cooperate and interact
   with print service providers.  This model and semantics document
   describes a simple, abstract model for IPP even though the underlying
   configurations may be complex "n-tier" client/server systems.  An
   important simplifying step in the IPP model is to expose only the key
   objects and interfaces required for printing.  The model described in
   this model document does not include features, interfaces, and
   relationships that are beyond the scope of the first version of IPP
   (IPP/1.1).  IPP/1.1 incorporates many of the relevant ideas and
   lessons learned from other specification and development efforts
   [HTPP] [ISO10175] [LDPA] [P1387.4] [PSIS] [RFC1179] [SWP].  IPP is
   heavily influenced by the printing model introduced in the Document
   Printing Application (DPA) [ISO10175] standard.  Although DPA
   specifies both end user and administrative features, IPP version 1.1
   (IPP/1.1) focuses primarily on end user functionality with a few
   additional OPTIONAL operator operations.

   The IPP/1.1 model encapsulates the important components of
   distributed printing into two object types:

      - Printer (Section 2.1)
      - Job (Section 2.2)

   Each object type has an associated set of operations (see section 3)
   and attributes (see section 4).








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   It is important, however, to understand that in real system
   implementations (which lie underneath the abstracted IPP/1.1 model),
   there are other components of a print service which are not
   explicitly defined in the IPP/1.1 model. The following figure
   illustrates where IPP/1.1 fits with respect to these other
   components.

                                +--------------+
                                |  Application |
                      o         +. . . . . . . |
                     \|/        |   Spooler    |
                     / \        +. . . . . . . |   +---------+
                   End-User     | Print Driver |---|  File   |
         +-----------+ +-----+  +------+-------+   +----+----+
         |  Browser  | | GUI |         |                |
         +-----+-----+ +--+--+         |                |
               |          |            |                |
               |      +---+------------+---+            |
   N   D   S   |      |      IPP Client    |------------+
   O   I   E   |      +---------+----------+
   T   R   C   |                |
   I   E   U   |
   F   C   R   -------------- Transport ------------------
   I   T   I
   C   O   T                    |         --+
   A   R   Y           +--------+--------+  |
   T   Y               |    IPP Server   |  |
   I                   +--------+--------+  |
   O                            |           |
   N                   +-----------------+  | IPP Printer
                       |  Print Service  |  |
                       +-----------------+  |
                                |         --+
                       +-----------------+
                       | Output Device(s)|
                       +-----------------+

   An IPP Printer object encapsulates the functions normally associated
   with physical output devices along with the spooling, scheduling and
   multiple device management functions often associated with a print
   server. Printer objects are optionally registered as entries in a
   directory where end users find and select them based on some sort of
   filtered and context based searching mechanism (see section 16).  The
   directory is used to store relatively static information about the
   Printer, allowing end users to search for and find Printers that
   match their search criteria, for example: name, context, printer
   capabilities, etc.  The more dynamic information, such as state,
   currently loaded and ready media, number of jobs at the Printer,



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   errors, warnings, and so forth, is directly associated with the
   Printer object itself rather than with the entry in the directory
   which only represents the Printer object.

   IPP clients implement the IPP protocol on the client side and give
   end users (or programs running on behalf of end users) the ability to
   query Printer objects and submit and manage print jobs.  An IPP
   server is just that part of the Printer object that implements the
   server-side protocol.  The rest of the Printer object implements (or
   gateways into) the application semantics of the print service itself.
   The Printer objects may be embedded in an output device or may be
   implemented on a host on the network that communicates with an output
   device.

   When a job is submitted to the Printer object and the Printer object
   validates the attributes in the submission request, the Printer
   object creates a new Job object.  The end user then interacts with
   this new Job object to query its status and monitor the progress of
   the job.  An end user can also cancel their print jobs by using the
   Job object's Cancel-Job operation.  An end-user can also hold,
   release, and restart their print jobs using the Job object's OPTIONAL
   Hold-Job, Release-Job, and Restart-Job operations, if implemented.

   A privileged operator or administrator of a Printer object can
   cancel, hold, release, and restart any user's job using the REQUIRED
   Cancel-Job and the OPTIONAL Hold-Job, Release-Job, and Restart-Job
   operations.  In additional privileged operator or administrator of a
   Printer object can pause, resume, or purge (jobs from) a Printer
   object using the OPTIONAL Pause-Printer, Resume-Printer, and Purge-
   Jobs operations, if implemented.

   The notification service is out of scope for this IPP/1.1 document,
   but using such a notification service, the end user is able to
   register for and receive Printer specific and Job specific events.
   An end user can query the status of Printer objects and can follow
   the progress of Job objects by polling using the Get-Printer-
   Attributes, Get-Jobs, and Get-Job-Attributes operations.

2. IPP Objects



   The IPP/1.1 model introduces objects of type Printer and Job.  Each
   type of object models relevant aspects of a real-world entity such as
   a real printer or real print job.  Each object type is defined as a
   set of possible attributes that may be supported by instances of that
   object type.  For each object (instance), the actual set of supported
   attributes and values describe a specific implementation.  The
   object's attributes and values describe its state, capabilities,
   realizable features, job processing functions, and default behaviors



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   and characteristics.  For example, the Printer object type is defined
   as a set of attributes that each Printer object potentially supports.
   In the same manner, the Job object type is defined as a set of
   attributes that are potentially supported by each Job object.

   Each attribute included in the set of attributes defining an object
   type is labeled as:

   - "REQUIRED": each object MUST support the attribute.
   - "RECOMMENDED": each object SHOULD support the attribute.
   - "OPTIONAL": each object MAY support the attribute.

   Some definitions of attribute values indicate that an object MUST or
   SHOULD support the value; otherwise, support of the value is
   OPTIONAL.

   However, if an implementation supports an attribute, it MUST support
   at least one of the possible values for that attribute.

2.1 Printer Object



   The major component of the IPP/1.1 model is the Printer object.  A
   Printer object implements the server-side of the IPP/1.1 protocol.
   Using the protocol, end users may query the attributes of the Printer
   object and submit print jobs to the Printer object.  The actual
   implementation components behind the Printer abstraction may take on
   different forms and different configurations.  However, the model
   abstraction allows the details of the configuration of real
   components to remain opaque to the end user.  Section 3 describes
   each of the Printer operations in detail.

   The capabilities and state of a Printer object are described by its
   attributes.  Printer attributes are divided into two groups:

   - "job-template" attributes: These attributes describe supported job
     processing capabilities and defaults for the Printer object. (See
     section 4.2)
   - "printer-description" attributes: These attributes describe the
     Printer object's identification, state, location, references to
     other sources of information about the Printer object, etc. (see
     section 4.4)

   Since a Printer object is an abstraction of a generic document output
   device and print service provider, a Printer object could be used to
   represent any real or virtual device with semantics consistent with
   the Printer object, such as a fax device, an imager, or even a CD
   writer.




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   Some examples of configurations supporting a Printer object include:

      1) An output device with no spooling capabilities
      2) An output device with a built-in spooler
      3) A print server supporting IPP with one or more associated
         output devices
         3a) The associated output devices may or may not be capable of
             spooling jobs
         3b) The associated output devices may or may not support IPP

   The following figures show some examples of how Printer objects can
   be realized on top of various distributed printing configurations.
   The embedded case below represents configurations 1 and 2. The hosted
   and fan-out figures below represent configurations 3a and 3b.

   In this document the term "client" refers to a software entity that
   sends IPP operation requests to an IPP Printer object and accepts IPP
   operation responses.  A client MAY be:

      1. contained within software controlled by an end user, e.g.
         activated by the "Print" menu item in an application or

      2. the print server component that sends IPP requests to either an
         output device or another "downstream" print server.

   The term "IPP Printer" is a network entity that accepts IPP operation
   requests and returns IPP operation responses.  As such, an IPP object
   MAY be:

      1. an (embedded) device component that accepts IPP requests and
         controls the device or

      2. a component of a print server that accepts IPP requests (where
         the print server controls one or more networked devices using
         IPP or other protocols).

   Legend:

   ##### indicates a Printer object which is
         either embedded in an output device or is
         hosted in a server.  The Printer object
         might or might not be capable of queuing/spooling.

   any   indicates any network protocol or direct
         connect, including IPP






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   embedded printer:
                                             output device
                                           +---------------+
    O   +--------+                         |  ###########  |
   /|\  | client |------------IPP------------># Printer #  |
   / \  +--------+                         |  # Object  #  |
                                           |  ###########  |
                                           +---------------+

   hosted printer:
                                           +---------------+
    O   +--------+        ###########      |               |
   /|\  | client |--IPP--># Printer #-any->| output device |
   / \  +--------+        # Object  #      |               |
                          ###########      +---------------+


                                            +---------------+
   fan out:                                 |               |
                                        +-->| output device |
                                    any/    |               |
    O   +--------+      ###########   /     +---------------+
   /|\  | client |-IPP-># Printer #--*
   / \  +--------+      # Object  #   \     +---------------+
                        ########### any\    |               |
                                        +-->| output device |
                                            |               |
                                            +---------------+

2.2 Job Object



   A Job object is used to model a print job.  A Job object contains
   documents.  The information required to create a Job object is sent
   in a create request from the end user via an IPP Client to the
   Printer object.  The Printer object validates the create request, and
   if the Printer object accepts the request, the Printer object creates
   the new Job object.  Section 3 describes each of the Job operations
   in detail.

   The characteristics and state of a Job object are described by its
   attributes.  Job attributes are grouped into two groups as follows:

      - "job-template" attributes: These attributes can be supplied by
        the client or end user and include job processing instructions
        which are intended to override any Printer object defaults
        and/or instructions embedded within the document data. (See
        section 4.2)




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      - "job-description" attributes: These attributes describe the Job
        object's identification, state, size, etc. The client supplies
        some of these attributes, and the Printer object generates
        others. (See section 4.3)

   An implementation MUST support at least one document per Job object.
   An implementation MAY support multiple documents per Job object.  A
   document is either:

      - a stream of document data in a format supported by the Printer
        object (typically a Page Description Language - PDL), or
      - a reference to such a stream of document data

   In IPP/1.1, a document is not modeled as an IPP object, therefore it
   has no object identifier or associated attributes.  All job
   processing instructions are modeled as Job object attributes.  These
   attributes are called Job Template attributes and they apply equally
   to all documents within a Job object.

2.3 Object Relationships



   IPP objects have relationships that are maintained persistently along
   with the persistent storage of the object attributes.

   A Printer object can represent either one or more physical output
   devices or a logical device which "processes" jobs but never actually
   uses a physical output device to put marks on paper.  Examples of
   logical devices include a Web page publisher or a gateway into an
   online document archive or repository.  A Printer object contains
   zero or more Job objects.

   A Job object is contained by exactly one Printer object, however the
   identical document data associated with a Job object could be sent to
   either the same or a different Printer object.  In this case, a
   second Job object would be created which would be almost identical to
   the first Job object, however it would have new (different) Job
   object identifiers (see section 2.4).

   A Job object is either empty (before any documents have been added)
   or contains one or more documents.  If the contained document is a
   stream of document data, that stream can be contained in only one
   document.  However, there can be identical copies of the stream in
   other documents in the same or different Job objects.  If the
   contained document is just a reference to a stream of document data,
   other documents (in the same or different Job object(s)) may contain
   the same reference.





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2.4 Object Identity



   All Printer and Job objects are identified by a Uniform Resource
   Identifier (URI) [RFC2396] so that they can be persistently and
   unambiguously referenced.  Since every URL is a specialized form of a
   URI, even though the more generic term URI is used throughout the
   rest of this document, its usage is intended to cover the more
   specific notion of URL as well.

   An administrator configures Printer objects to either support or not
   support authentication and/or message privacy using Transport Layer
   Security (TLS) [RFC2246] (the mechanism for security configuration is
   outside the scope of this IPP/1.1 document).  In some situations,
   both types of connections (both authenticated and unauthenticated)
   can be established using a single communication channel that has some
   sort of negotiation mechanism.  In other situations, multiple
   communication channels are used, one for each type of security
   configuration.  Section 8 provides a full description of all security
   considerations and configurations.

   If a Printer object supports more than one communication channel,
   some or all of those channels might support and/or require different
   security mechanisms.  In such cases, an administrator could expose
   the simultaneous support for these multiple communication channels as
   multiple URIs for a single Printer object where each URI represents
   one of the communication channels to the Printer object. To support
   this flexibility, the IPP Printer object type defines a multi-valued
   identification attribute called the "printer-uri-supported"
   attribute.  It MUST contain at least one URI.  It MAY contain more
   than one URI.  That is, every Printer object will have at least one
   URI that identifies at least one communication channel to the Printer
   object, but it may have more than one URI where each URI identifies a
   different communication channel to the Printer object.  The
   "printer-uri-supported" attribute has two companion attributes, the
   "uri-security-supported" attribute and the "uri-authentication-
   supported". Both have the same cardinality as "printer-uri-
   supported".  The purpose of the "uri-security-supported" attribute is
   to indicate the security mechanisms (if any) used for each URI listed
   in "printer-uri-supported". The purpose of the "uri-authentication-
   supported" attribute is to indicate the authentication mechanisms (if
   any) used for each URI listed in "printer-uri-supported".  These
   three attributes are fully described in sections 4.4.1, 4.4.2, and
   4.4.3.

   When a job is submitted to the Printer object via a create request,
   the client supplies only a single Printer object URI.  The client
   supplied Printer object URI MUST be one of the values in the
   "printer-uri-supported" Printer attribute.



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   IPP/1.1 does not specify how the client obtains the client supplied
   URI, but it is RECOMMENDED that a Printer object be registered as an
   entry in a directory service.  End-users and programs can then
   interrogate the directory searching for Printers. Section 16 defines
   a generic schema for Printer object entries in the directory service
   and describes how the entry acts as a bridge to the actual IPP
   Printer object.  The entry in the directory that represents the IPP
   Printer object includes the possibly many URIs for that Printer
   object as values in one its attributes.

   When a client submits a create request to the Printer object, the
   Printer object validates the request and creates a new Job object.
   The Printer object assigns the new Job object a URI which is stored
   in the "job-uri" Job attribute.  This URI is then used by clients as
   the target for subsequent Job operations.  The Printer object
   generates a Job URI based on its configured security policy and the
   URI used by the client in the create request.

   For example, consider a Printer object that supports both a
   communication channel secured by the use of SSL3 (using HTTP over
   SSL3 with an "https" schemed URI) and another open communication
   channel that is not secured with SSL3 (using a simple "http" schemed
   URI).  If a client were to submit a job using the secure URI, the
   Printer object would assign the new Job object a secure URI as well.
   If a client were to submit a job using the open-channel URI, the
   Printer would assign the new Job object an open-channel URI.

   In addition, the Printer object also populates the Job object's
   "job-printer-uri" attribute.  This is a reference back to the Printer
   object that created the Job object.  If a client only has access to a
   Job object's "job-uri" identifier, the client can query the Job's
   "job-printer-uri" attribute in order to determine which Printer
   object created the Job object.  If the Printer object supports more
   than one URI, the Printer object picks the one URI supplied by the
   client when creating the job to build the value for and to populate
   the Job's "job-printer-uri" attribute.

   Allowing Job objects to have URIs allows for flexibility and
   scalability.  For example, in some implementations, the Printer
   object might create Jobs that are processed in the same local
   environment as the Printer object itself.  In this case, the Job URI
   might just be a composition of the Printer's URI and some unique
   component for the Job object, such as the unique 32-bit positive
   integer mentioned later in this paragraph.  In other implementations,
   the Printer object might be a central clearing-house for validating
   all Job object creation requests, but the Job object itself might be
   created in some environment that is remote from the Printer object.
   In this case, the Job object's URI may have no physical-location



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   relationship at all to the Printer object's URI.  Again, the fact
   that Job objects have URIs allows for flexibility and scalability,
   however, many existing printing systems have local models or
   interface constraints that force print jobs to be identified using
   only a 32-bit positive integer rather than an independent URI.  This
   numeric Job ID is only unique within the context of the Printer
   object to which the create request was originally submitted.
   Therefore, in order to allow both types of client access to IPP Job
   objects (either by Job URI or by numeric Job ID), when the Printer
   object successfully processes a create request and creates a new Job
   object, the Printer object MUST generate both a Job URI and a Job ID.
   The Job ID (stored in the "job-id" attribute) only has meaning in the
   context of the Printer object to which the create request was
   originally submitted. This requirement to support both Job URIs and
   Job IDs allows all types of clients to access Printer objects and Job
   objects no matter the local constraints imposed on the client
   implementation.

   In addition to identifiers, Printer objects and Job objects have
   names ("printer-name" and "job-name").  An object name NEED NOT be
   unique across all instances of all objects. A Printer object's name
   is chosen and set by an administrator through some mechanism outside
   the scope of this IPP/1.1 document.  A Job object's name is
   optionally chosen and supplied by the IPP client submitting the job.
   If the client does not supply a Job object name, the Printer object
   generates a name for the new Job object.  In all cases, the name only
   has local meaning.

   To summarize:

      - Each Printer object is identified with one or more URIs.  The
        Printer's "printer-uri-supported" attribute contains the URI(s).
      - The Printer object's "uri-security-supported" attribute
        identifies the communication channel security protocols that may
        or may not have been configured for the various Printer object
        URIs (e.g., 'tls' or 'none').
      - The Printer object's "uri-authentication-supported" attribute
        identifies the authentication mechanisms that may or may not
        have been configured for the various Printer object URIs (e.g.,
        'digest' or 'none').
      - Each Job object is identified with a Job URI.  The Job's "job-
        uri" attribute contains the URI.
      - Each Job object is also identified with Job ID which is a 32-
        bit, positive integer.  The Job's "job-id" attribute contains
        the Job ID.  The Job ID is only unique within the context of the
        Printer object  which created the Job object.





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      - Each Job object has a "job-printer-uri" attribute which contains
        the URI of the Printer object that was used to create the Job
        object.  This attribute is used to determine the Printer object
        that created a Job object when given only the URI for the Job
        object.  This linkage is necessary to determine the languages,
        charsets, and operations which are supported on that Job (the
        basis for such support comes from the creating Printer object).
      - Each Printer object has a name (which is not necessarily
        unique).  The administrator chooses and sets this name through
        some mechanism outside the scope of this IPP/1.1 document.  The
        Printer object's "printer-name" attribute contains the name.
      - Each Job object has a name (which is not necessarily unique).
        The client optionally supplies this name in the create request.
        If the client does not supply this name, the Printer object
        generates a name for the Job object. The Job object's "job-name"
        attribute contains the name.

3. IPP Operations



   IPP objects support operations.  An operation consists of a request
   and a response.  When a client communicates with an IPP object, the
   client issues an operation request to the URI for that object.
   Operation requests and responses have parameters that identify the
   operation.  Operations also have attributes that affect the run-time
   characteristics of the operation (the intended target, localization
   information, etc.).  These operation-specific attributes are called
   operation attributes (as compared to object attributes such as
   Printer object attributes or Job object attributes).  Each request
   carries along with it any operation attributes, object attributes,
   and/or document data required to perform the operation.  Each request
   requires a response from the object.  Each response indicates success
   or failure of the operation with a status code as a response
   parameter.  The response contains any operation attributes, object
   attributes, and/or status messages generated during the execution of
   the operation request.

   This section describes the semantics of the IPP operations, both
   requests and responses, in terms of the parameters, attributes, and
   other data associated with each operation.












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   The IPP/1.1 Printer operations are:

     Print-Job (section 3.2.1)
     Print-URI (section 3.2.2)
     Validate-Job (section 3.2.3)
     Create-Job (section 3.2.4)
     Get-Printer-Attributes (section 3.2.5)
     Get-Jobs (section 3.2.6)
     Pause-Printer (section 3.3.5)
     Resume-Printer (section 3.3.6)
     Purge-Jobs (section 3.3.7)

   The Job operations are:

     Send-Document (section 3.3.1)
     Send-URI (section 3.3.2)
     Cancel-Job (section 3.3.3)
     Get-Job-Attributes (section 3.3.4)
     Hold-Job (section 3.3.5)
     Release-Job (section 3.3.6)
     Restart-Job (section 3.3.7)

   The Send-Document and Send-URI Job operations are used to add a new
   document to an existing multi-document Job object created using the
   Create-Job operation.

3.1 Common Semantics



   All IPP operations require some common parameters and operation
   attributes.  These common elements and their semantic characteristics
   are defined and described in more detail in the following sections.

3.1.1 Required Parameters



   Every operation request contains the following REQUIRED parameters:

      - a "version-number",
      - an "operation-id",
      - a "request-id", and
      - the attributes that are REQUIRED for that type of request.

   Every operation response contains the following REQUIRED parameters:

      - a "version-number",
      - a "status-code",
      - the "request-id" that was supplied in the corresponding request,
        and
      - the attributes that are REQUIRED for that type of response.



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   The "Encoding and Transport" document [RFC2910] defines special rules
   for the encoding of these parameters.  All other operation elements
   are represented using the more generic encoding rules for attributes
   and groups of attributes.

3.1.2 Operation IDs and Request IDs



   Each IPP operation request includes an identifying "operation-id"
   value.  Valid values are defined in the "operations-supported"
   Printer attribute section (see section 4.4.15).  The client specifies
   which operation is being requested by supplying the correct
   "operation-id" value.

   In addition, every invocation of an operation is identified by a
   "request-id" value. For each request, the client chooses the
   "request-id" which MUST be an integer (possibly unique depending on
   client requirements) in the range from 1 to 2**31 - 1 (inclusive).
   This "request-id" allows clients to manage multiple outstanding
   requests. The receiving IPP object copies all 32-bits of the client-
   supplied "request-id" attribute into the response so that the client
   can match the response with the correct outstanding request, even if
   the "request-id" is out of range.  If the request is terminated
   before the complete "request-id" is received, the IPP object rejects
   the request and returns a response with a "request-id" of 0.

   Note: In some cases, the transport protocol underneath IPP might be a
   connection oriented protocol that would make it impossible for a
   client to receive responses in any order other than the order in
   which the corresponding requests were sent.  In such cases, the
   "request-id" attribute would not be essential for correct protocol
   operation.  However, in other mappings, the operation responses can
   come back in any order.  In these cases, the "request-id" would be
   essential.

3.1.3 Attributes



   Operation requests and responses are both composed of groups of
   attributes and/or document data.  The attributes groups are:

      - Operation Attributes: These attributes are passed in the
        operation and affect the IPP object's behavior while processing
        the operation request and may affect other attributes or groups
        of attributes.  Some operation attributes describe the document
        data associated with the print job and are associated with new
        Job objects, however most operation attributes do not persist
        beyond the life of the operation.  The description of each
        operation attribute includes conformance statements indicating
        which operation attributes are REQUIRED and which are OPTIONAL



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        for an IPP object to support and which attributes a client MUST
        supply in a request and an IPP object MUST supply in a response.
      - Job Template Attributes: These attributes affect the processing
        of a job.  A client OPTIONALLY supplies Job Template Attributes
        in a create request, and the receiving object MUST be prepared
        to receive all supported attributes.  The Job object can later
        be queried to find out what Job Template attributes were
        originally requested in the create request, and such attributes
        are returned in the response as Job Object Attributes.  The
        Printer object can be queried about its Job Template attributes
        to find out what type of job processing capabilities are
        supported and/or what the default job processing behaviors are,
        though such attributes are returned in the response as Printer
        Object Attributes.  The "ipp-attribute-fidelity" operation
        attribute affects processing of all client-supplied Job Template
        attributes (see sections 3.2.1.2 and 15 for a full description
        of "ipp-attribute-fidelity" and its relationship to other
        attributes).
      - Job Object Attributes: These attributes are returned in response
        to a query operation directed at a Job object.
      - Printer Object Attributes: These attributes are returned in
        response to a query operation directed at a Printer object.
      - Unsupported Attributes: In a create request, the client supplies
        a set of Operation and Job Template attributes.  If any of these
        attributes or their values is unsupported by the Printer object,
        the Printer object returns the set of unsupported attributes in
        the response.  Sections 3.1.7, 3.2.1.2, and  15 give a full
        description of how Job Template attributes supplied by the
        client in a create request are processed by the Printer object
        and how unsupported attributes are returned to the client.
        Because of extensibility, any IPP object might receive a request
        that contains new or unknown attributes or values for which it
        has no support. In such cases, the IPP object processes what it
        can and returns the unsupported attributes in the response. The
        Unsupported Attribute group is defined for all operation
        responses for returning unsupported attributes that the client
        supplied in the request.

   Later in this section, each operation is formally defined by
   identifying the allowed and expected groups of attributes for each
   request and response.  The model identifies a specific order for each
   group in each request or response, but the attributes within each
   group may be in any order, unless specified otherwise.

   The attributes within a group MUST be unique; if an attribute with
   the same name occurs more than once, the group is mal-formed.
   Clients MUST NOT submit such malformed requests and Printers MUST NOT
   return such malformed responses.  If such a malformed request is



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   submitted to a Printer, the Printer MUST either (1) reject the
   request with the 'client-error-bad-request' status code (see section
   13.1.4.1) or (2) process the request normally after selecting only
   one of the attribute instances, depending on implementation.  Which
   attribute is selected when there are duplicate attributes depends on
   implementation.  The IPP Printer MUST NOT use the values from more
   than one such duplicate attribute instance.

   Each attribute definition includes the attribute's name followed by
   the name of its attribute syntax(es) in parenthesizes.  In addition,
   each 'integer' attribute is followed by the allowed range in
   parentheses, (m:n), for values of that attribute.  Each 'text' or
   'name' attribute is followed by the maximum size in octets in
   parentheses, (size), for values of that attribute. For more details
   on attribute syntax notation, see the descriptions of these
   attributes syntaxes in section 4.1.

   Note: Document data included in the operation is not strictly an
   attribute, but it is treated as a special attribute group for
   ordering purposes.  The only operations that support supplying the
   document data within an operation request are Print-Job and Send-
   Document.  There are no operation responses that include document
   data.

   Some operations are REQUIRED for IPP objects to support; the others
   are OPTIONAL (see section 5.2.2).  Therefore, before using an
   OPTIONAL operation, a client SHOULD first use the REQUIRED Get-
   Printer-Attributes operation to query the Printer's "operations-
   supported" attribute in order to determine which OPTIONAL Printer and
   Job operations are actually supported.  The client SHOULD NOT use an
   OPTIONAL operation that is not supported.  When an IPP object
   receives a request to perform an operation it does not support, it
   returns the 'server-error-operation-not-supported' status code (see
   section 13.1.5.2).  An IPP object is non-conformant if it does not
   support a REQUIRED operation.

3.1.4 Character Set and Natural Language Operation Attributes



   Some Job and Printer attributes have values that are text strings and
   names intended for human understanding rather than machine
   understanding (see the 'text' and 'name' attribute syntax
   descriptions in section 4.1).  The following sections describe two
   special Operation Attributes called "attributes-charset" and
   "attributes-natural-language".  These attributes are always part of
   the Operation Attributes group.  For most attribute groups, the order
   of the attributes within the group is not important.  However, for
   these two attributes within the Operation Attributes group, the order
   is critical.  The "attributes-charset" attribute MUST be the first



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   attribute in the group and the "attributes-natural-language"
   attribute MUST be the second attribute in the group.  In other words,
   these attributes MUST be supplied in every IPP request and response,
   they MUST come first in the group, and MUST come in the specified
   order.  For job creation operations, the IPP Printer implementation
   saves these two attributes with the new Job object as Job Description
   attributes.  For the sake of brevity in this document, these
   operation attribute descriptions are not repeated with every
   operation request and response, but have a reference back to this
   section instead.

3.1.4.1 Request Operation Attributes



   The client MUST supply and the Printer object MUST support the
   following REQUIRED operation attributes in every IPP/1.1 operation
   request:

      "attributes-charset" (charset):
         This operation attribute identifies the charset (coded
         character set and encoding method) used by any 'text' and
         'name' attributes that the client is supplying in this request.
         It also identifies the charset that the Printer object MUST use
         (if supported) for all 'text' and 'name' attributes and status
         messages that the Printer object returns in the response to
         this request. See Sections 4.1.1 and 4.1.2 for the definition
         of the 'text' and 'name' attribute syntaxes.

         All clients and IPP objects MUST support the 'utf-8' charset
         [RFC2279] and MAY support additional charsets provided that
         they are registered with IANA [IANA-CS].  If the Printer object
         does not support the client supplied charset value, the Printer
         object MUST reject the request, set the "attributes-charset" to
         'utf-8' in the response, and return the 'client-error-charset-
         not-supported' status code and any 'text' or 'name' attributes
         using the 'utf-8' charset. The Printer NEED NOT return any
         attributes in the Unsupported Attributes Group (See sections
         3.1.7 and 3.2.1.2).  The Printer object MUST indicate the
         charset(s) supported as the values of the "charset-supported"
         Printer attribute (see Section 4.4.18), so that the client can
         query to determine which charset(s) are supported.

         Note to client implementers: Since IPP objects are only
         required to support the 'utf-8' charset, in order to maximize
         interoperability with multiple IPP object implementations, a
         client may want to supply 'utf-8' in the "attributes-charset"
         operation attribute, even though the client is only passing and
         able to present a simpler charset, such as US-ASCII [ASCII] or
         ISO-8859-1 [ISO8859-1].  Then the client will have to filter



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         out (or charset convert) those characters that are returned in
         the response that it cannot present to its user.  On the other
         hand, if both the client and the IPP objects also support a
         charset in common besides utf-8, the client may want to use
         that charset in order to avoid charset conversion or data loss.

         See the 'charset' attribute syntax description in Section 4.1.7
         for the syntax and semantic interpretation of the values of
         this attribute and for example values.

      "attributes-natural-language" (naturalLanguage):
         This operation attribute identifies the natural language used
         by any 'text' and 'name' attributes that the client is
         supplying in this request.  This attribute also identifies the
         natural language that the Printer object SHOULD use for all
         'text' and 'name' attributes and status messages that the
         Printer object returns in the response to this request.  See
         the 'naturalLanguage' attribute syntax description in section
         4.1.8 for the syntax and semantic interpretation of the values
         of this attribute and for example values.

         There are no REQUIRED natural languages required for the
         Printer object to support.  However, the Printer object's
         "generated-natural-language-supported" attribute identifies the
         natural languages supported by the Printer object and any
         contained Job objects for all text strings generated by the IPP
         object.  A client MAY query this attribute to determine which
         natural language(s) are supported for generated messages.

         For any of the attributes for which the Printer object
         generates text, i.e., for the "job-state-message", "printer-
         state-message", and status messages (see Section 3.1.6), the
         Printer object MUST be able to generate these text strings in
         any of its supported natural languages.  If the client requests
         a natural language that is not supported, the Printer object
         MUST return these generated messages in the Printer's
         configured natural language as specified by the Printer's
         "natural-language-configured" attribute" (see Section 4.4.19).

         For other 'text' and 'name' attributes supplied by the client,
         authentication system, operator, system administrator, or
         manufacturer (i.e., for "job-originating-user-name", "printer-
         name" (name), "printer-location" (text), "printer-info" (text),
         and "printer-make-and-model" (text)), the Printer object is
         only required to support the configured natural language of the






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         Printer identified by the Printer object's "natural-language-
         configured" attribute, though support of additional natural
         languages for these attributes is permitted.

         For any 'text' or 'name' attribute in the request that is in a
         different natural language than the value supplied in the
         "attributes-natural-language" operation attribute, the client
         MUST use the Natural Language Override mechanism (see sections
         4.1.1.2 and 4.1.2.2) for each such attribute value supplied.
         The client MAY use the Natural Language Override mechanism
         redundantly, i.e., use it even when the value is in the same
         natural language as the value supplied in the "attributes-
         natural-language" operation attribute of the request.

         The IPP object MUST accept any natural language and any Natural
         Language Override, whether the IPP object supports that natural
         language or not (and independent of the value of the "ipp-
         attribute-fidelity" Operation attribute).  That is the IPP
         object accepts all client supplied values no matter what the
         values are in the Printer object's "generated-natural-
         language-supported" attribute.  That attribute, "generated-
         natural-language-supported", only applies to generated
         messages, not client supplied messages.  The IPP object MUST
         remember that natural language for all client-supplied
         attributes, and when returning those attributes in response to
         a query, the IPP object MUST indicate that natural language.

         Each value whose attribute syntax type is 'text' or 'name' (see
         sections 4.1.1 and 4.1.2) has an Associated Natural-Language.
         This document does not specify how this association is stored
         in a Printer or Job object.  When such a value is encoded in a
         request or response, the natural language is either implicit or
         explicit:

         - In the implicit case, the value contains only the text/name
           value, and the language is specified by the "attributes-
           natural-language" operation attribute in the request or
           response (see sections 4.1.1.1 textWithoutLanguage and
           4.1.2.1 nameWithoutLanguage).

         - In the explicit case (also known as the Natural-Language
           Override case), the value contains both the language and the
           text/name value (see sections 4.1.1.2 textWithLanguage and
           4.1.2.2 nameWithLanguage).

         For example, the "job-name" attribute MAY be supplied by the
         client in a create request.  The text value for this attribute
         will be in the natural language identified by the "attribute-



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         natural-language" attribute, or if different, as identified by
         the Natural Language Override mechanism.  If supplied, the IPP
         object will use the value of the "job-name" attribute to
         populate the Job object's "job-name" attribute.  Whenever any
         client queries the Job object's "job-name" attribute, the IPP
         object returns the attribute as stored and uses the Natural
         Language Override mechanism to specify the natural language, if
         it is different from that reported in the "attributes-natural-
         language" operation attribute of the response.  The IPP object
         MAY use the Natural Language Override mechanism redundantly,
         i.e., use it even when the value is in the same natural
         language as the value supplied in the "attributes-natural-
         language" operation attribute of the response.

         An IPP object MUST NOT reject a request based on a supplied
         natural language in an "attributes-natural-language" Operation
         attribute or in any attribute that uses the Natural Language
         Override.

   Clients SHOULD NOT supply 'text' or 'name' attributes that use an
   illegal combination of natural language and charset.  For example,
   suppose a Printer object supports charsets 'utf-8', 'iso-8859-1', and
   'iso-8859-7'.  Suppose also, that it supports natural languages 'en'
   (English), 'fr' (French), and 'el' (Greek).  Although the Printer
   object supports the charset 'iso-8859-1' and natural language 'el',
   it probably does not support the combination of Greek text strings
   using the 'iso-8859-1' charset.  The Printer object handles this
   apparent incompatibility differently depending on the context in
   which it occurs:

      - In a create request: If the client supplies a text or name
        attribute (for example, the "job-name" operation attribute) that
        uses an apparently incompatible combination, it is a client
        choice that does not affect the Printer object or its correct
        operation.  Therefore, the Printer object simply accepts the
        client supplied value, stores it with the Job object, and
        responds back with the same combination whenever the client (or
        any client) queries for that attribute.
      - In a query-type operation, like Get-Printer-Attributes: If the
        client requests an apparently incompatible combination, the
        Printer object responds (as described in section 3.1.4.2) using
        the Printer's configured natural language rather than the
        natural language requested by the client.

   In either case, the Printer object does not reject the request
   because of the apparent incompatibility.  The potential incompatible
   combination of charset and natural language can occur either at the
   global operation level or at the Natural Language Override



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   attribute-by-attribute level.  In addition, since the response always
   includes explicit charset and natural language information, there is
   never any question or ambiguity in how the client interprets the
   response.

3.1.4.2 Response Operation Attributes



   The Printer object MUST supply and the client MUST support the
   following REQUIRED operation attributes in every IPP/1.1 operation
   response:

      "attributes-charset" (charset):
         This operation attribute identifies the charset used by any
         'text' and 'name' attributes that the Printer object is
         returning in this response.  The value in this response MUST be
         the same value as the "attributes-charset" operation attribute
         supplied by the client in the request.  If this is not possible
         (i.e., the charset requested is not supported), the request
         would have been rejected.  See "attributes-charset" described
         in Section 3.1.4.1 above.

         If the Printer object supports more than just the 'utf-8'
         charset, the Printer object MUST be able to code convert
         between each of the charsets supported on a highest fidelity
         possible basis in order to return the 'text' and 'name'
         attributes in the charset requested by the client.  However,
         some information loss MAY occur during the charset conversion
         depending on the charsets involved.  For example, the Printer
         object may convert from a UTF-8 'a' to a US-ASCII 'a' (with no
         loss of information), from an ISO Latin 1 CAPITAL LETTER A WITH
         ACUTE ACCENT to US-ASCII 'A' (losing the accent), or from a
         UTF-8 Japanese Kanji character to some ISO Latin 1 error
         character indication such as '?', decimal code equivalent, or
         to the absence of a character, depending on implementation.

         Whether an implementation that supports more than one charset
         stores the data in the charset supplied by the client or code
         converts to one of the other supported charsets, depends on
         implementation.  The strategy should try to minimize loss of
         information during code conversion.  On each response, such an
         implementation converts from its internal charset to that
         requested.

      "attributes-natural-language" (naturalLanguage):
         This operation attribute identifies the natural language used
         by any 'text' and 'name' attributes that the IPP object is
         returning in this response.  Unlike the "attributes-charset"
         operation attribute, the IPP object NEED NOT return the same



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         value as that supplied by the client in the request.  The IPP
         object MAY return the natural language of the Job object or the
         Printer's configured natural language as identified by the
         Printer object's "natural-language-configured" attribute,
         rather than the natural language supplied by the client.  For
         any 'text' or 'name' attribute or status message in the
         response that is in a different natural language than the value
         returned in the "attributes-natural-language" operation
         attribute, the IPP object MUST use the Natural Language
         Override mechanism (see sections 4.1.1.2 and 4.1.2.2) on each
         attribute value returned.  The IPP object MAY use the Natural
         Language Override mechanism redundantly, i.e., use it even when
         the value is in the same natural language as the value supplied
         in the "attributes-natural-language" operation attribute of the
         response.

3.1.5 Operation Targets



   All IPP operations are directed at IPP objects.  For Printer
   operations, the operation is always directed at a Printer object
   using one of its URIs (i.e., one of the values in the Printer
   object's "printer-uri-supported" attribute).  Even if the Printer
   object supports more than one URI, the client supplies only one URI
   as the target of the operation.  The client identifies the target
   object by supplying the correct URI in the "printer-uri (uri)"
   operation attribute.

   For Job operations, the operation is directed at either:

      - The Job object itself using the Job object's URI.  In this case,
        the client identifies the target object by supplying the correct
        URI in the "job-uri (uri)" operation attribute.
      - The Printer object that created the Job object using both the
        Printer objects URI and the Job object's Job ID.  Since the
        Printer object that created the Job object generated the Job ID,
        it MUST be able to correctly associate the client supplied Job
        ID with the correct Job object.  The client supplies the Printer
        object's URI in the "printer-uri (uri)" operation attribute and
        the Job object's Job ID in the "job-id (integer(1:MAX))"
        operation attribute.

   If the operation is directed at the Job object directly using the Job
   object's URI, the client MUST NOT include the redundant "job-id"
   operation attribute.







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   The operation target attributes are REQUIRED operation attributes
   that MUST be included in every operation request.  Like the charset
   and natural language attributes (see section 3.1.4), the operation
   target attributes are specially ordered operation attributes.  In all
   cases, the operation target attributes immediately follow the
   "attributes-charset" and "attributes-natural-language" attributes
   within the operation attribute group, however the specific ordering
   rules are:

      - In the case where there is only one operation target attribute
        (i.e., either only the "printer-uri" attribute or only the
        "job-uri" attribute), that attribute MUST be the third attribute
        in the operation attributes group.
      - In the case where Job operations use two operation target
        attributes (i.e., the "printer-uri" and "job-id" attributes),
        the "printer-uri" attribute MUST be the third attribute and the
        "job-id" attribute MUST be the fourth attribute.

   In all cases, the target URIs contained within the body of IPP
   operation requests and responses must be in absolute format rather
   than relative format (a relative URL identifies a resource with the
   scope of the HTTP server, but does not include scheme, host or port).

   The following rules apply to the use of port numbers in URIs that
   identify IPP objects:

      1. If the URI scheme allows the port number to be explicitly
         included in the URI string, and a port number is specified
         within the URI, then that port number MUST be used by the
         client to contact the IPP object.

      2. If the URI scheme allows the port number to be explicitly
         included in the URI string, and a port number is not specified
         within the URI, then default port number implied by that URI
         scheme MUST be used by the client to contact the IPP object.

      3. If the URI scheme does not allow an explicit port number to be
         specified within the URI, then the default port number implied
         by that URI MUST be used by the client to contact the IPP
         object.

   Note: The IPP "Encoding and Transport document [RFC2910] shows a
   mapping of IPP onto HTTP/1.1 [RFC2616] and defines a new default port
   number for using IPP over HTTP/1.1.







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3.1.6 Operation Response Status Codes and Status Messages



   Every operation response includes a REQUIRED "status-code" parameter
   and an OPTIONAL "status-message" operation attribute, and an OPTIONAL
   "detailed-status-message" operation attribute.  The Print-URI and
   Send-URI response MAY include an OPTIONAL "document-access-error"
   operation attribute.

3.1.6.1 "status-code" (type2 enum)



   The REQUIRED "status-code" parameter provides information on the
   processing of a request.

   The status code is intended for use by automata.  A client
   implementation of IPP SHOULD convert status code values into any
   localized message that has semantic meaning to the end user.

   The "status-code" value is a numeric value that has semantic meaning.
   The "status-code" syntax is similar to a "type2 enum" (see section
   4.1 on "Attribute Syntaxes") except that values can range only from
   0x0000 to 0x7FFF.  Section 13 describes the status codes, assigns the
   numeric values, and suggests a corresponding status message for each
   status code for use by the client when the user's natural language is
   English.

   If the Printer performs an operation with no errors and it encounters
   no problems, it MUST return the status code 'successful-ok' in the
   response.  See section 13.

   If the client supplies unsupported values for the following
   parameters or Operation attributes, the Printer object MUST reject
   the operation, NEED NOT return the unsupported attribute value in the
   Unsupported Attributes group, and MUST return the indicated status
   code:

        Parameter/Attribute                 Status code

        version-number      server-error-version-not-supported
        operation-id        server-error-operation-not-supported
        attributes-charset  client-error-charset-not-supported
        compression         client-error-compression-not-supported
        document-format     client-error-document-format-not-supported
        document-uri        client-error-uri-scheme-not-supported,
                             client-error-document-access-error

   If the client supplies unsupported values for other attributes, or
   unsupported attributes, the Printer returns the status code defined
   in section 3.1.7 on Unsupported Attributes.



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3.1.6.2 "status-message" (text(255))



   The OPTIONAL "status-message" operation attribute provides a short
   textual description of the status of the operation.  The "status-
   message" attribute's syntax is "text(255)", so the maximum length is
   255 octets (see section 4.1.1).  The status message is intended for
   the human end user.  If a response does include a "status-message"
   attribute, an IPP client NEED NOT examine or display the messages,
   however it SHOULD do so in some implementation specific manner.  The
   "status-message" is especially useful for a later version of a
   Printer object to return as supplemental information for the human
   user to accompany a status code that an earlier version of a client
   might not understand.

   If the Printer object supports the "status-message" operation
   attribute, the Printer object MUST be able to generate this message
   in any of the natural languages identified by the Printer object's
   "generated-natural-language-supported" attribute (see the
   "attributes-natural-language" operation attribute specified in
   section 3.1.4.1.  Section 13 suggests the text for the status message
   returned by the Printer for use with the English natural language.

   As described in section 3.1.4.1 for any returned 'text' attribute, if
   there is a choice for generating this message, the Printer object
   uses the natural language indicated by the value of the "attributes-
   natural-language" in the client request if supported, otherwise the
   Printer object uses the value in the Printer object's own "natural-
   language-configured" attribute.

   If the Printer object supports the "status-message" operation
   attribute, it SHOULD use the REQUIRED 'utf-8' charset to return a
   status message for the following error status codes (see section 13):
   'client-error-bad-request', 'client-error-charset-not-supported',
   'server-error-internal-error', 'server-error-operation-not-
   supported', and 'server-error-version-not-supported'.  In this case,
   it MUST set the value of the "attributes-charset" operation attribute
   to 'utf-8' in the error response.

3.1.6.3 "detailed-status-message" (text(MAX))



   The OPTIONAL "detailed-status-message" operation attribute provides
   additional more detailed technical and implementation-specific
   information about the operation.  The "detailed-status-message"
   attribute's syntax is "text(MAX)", so the maximum length is 1023
   octets (see section 4.1.1).    If the Printer objects supports the
   "detailed-status-message" operation attribute, the Printer NEED NOT
   localize the message, since it is intended for use by the system
   administrator or other experienced technical persons.  Localization



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   might obscure the technical meaning of such messages.  Clients MUST
   NOT
attempt to parse the value of this attribute.  See the
   "document-access-error" operation attribute (section 3.1.6.4) for
   additional errors that a program can process.

3.1.6.4 "document-access-error" (text(MAX))



   This OPTIONAL operation attribute provides additional information
   about any document access errors encountered by the Printer before it
   returned a response to the Print-URI (section 3.2.2) or Send-URI
   (section 3.3.1) operation.  For errors in the protocol identified by
   the URI scheme in the "document-uri" operation attribute, such as
   'http:' or 'ftp:', the error code is returned in parentheses,
   followed by the URI.  For example:

      (404) http://ftp.pwg.org/pub/pwg/ipp/new_MOD/ipp-model-v11.pdf

   Most Internet protocols use decimal error codes (unlike IPP), so the
   ASCII error code representation is in decimal.

3.1.7 Unsupported Attributes



   The Unsupported Attributes group contains attributes that are not
   supported by the operation. This group is primarily for the job
   creation operations, but all operations can return this group.

   A Printer object MUST include an Unsupported Attributes group in a
   response if the status code is one of the following:  'successful-
   ok-ignored-or-substituted-attributes', 'successful-ok-conflicting-
   attributes', 'client-error-attributes-or-values-not-supported' or
   'client-error-conflicting-attributes'.

   If the status code is one of the four specified in the preceding
   paragraph, the Unsupported Attributes group MUST contain all of those
   attributes and only those attributes that are:

      a. an Operation or Job Template attribute supplied in the request,
         and

      b. unsupported by the printer. See below for details on the three
         categories "unsupported" attributes.

   If the status code is one of those in the table in section 3.1.6.1,
   the Unsupported Attributes group NEED NOT contain the unsupported
   parameter or attribute indicated in that table.






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   If the Printer object is not returning any Unsupported Attributes in
   the response, the Printer object SHOULD omit Group 2 rather than
   sending an empty group.  However, a client MUST be able to accept an
   empty group.

   Unsupported attributes fall into three categories:

      1. The Printer object does not support the supplied attribute (no
         matter what the attribute syntax or value).

      2. The Printer object does support the attribute, but does not
         support some or all of the particular attribute syntaxes or
         values supplied by the client (i.e., the Printer object does
         not have those attribute syntaxes or values in its
         corresponding "xxx-supported" attribute).

      3. The Printer object does support the attributes and values
         supplied, but the particular values are in conflict with one
         another, because they violate a constraint, such as not being
         able to staple transparencies.

   In the case of an unsupported attribute name, the Printer object
   returns the client-supplied attribute with a substituted value of
   'unsupported'.  This value's syntax type is "out-of-band" and its
   encoding is defined by special rules for "out-of-band" values in the
   "Encoding and Transport" document [RFC2910].   Its value indicates no
   support for the attribute itself (see the beginning of section 4.1).

   In the case of a supported attribute with one or more unsupported
   attribute syntaxes or values, the Printer object simply returns the
   client-supplied attribute with the unsupported attribute syntaxes or
   values as supplied by the client.  This indicates support for the
   attribute, but no support for that particular attribute syntax or
   value.  If the client supplies a multi-valued attribute with more
   than one value and the Printer object supports the attribute but only
   supports a subset of the client-supplied attribute syntaxes or
   values, the Printer object

   MUST return only those attribute syntaxes or values that are
   unsupported.

   In the case of two (or more) supported attribute values that are in
   conflict with one another (although each is supported independently,
   the values conflict when requested together within the same job), the
   Printer object MUST return all the values that it ignores or
   substitutes to resolve the conflict, but not any of the values that





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   it is still using.  The choice for exactly how to resolve the
   conflict is implementation dependent.  See sections 3.2.1.2 and 15.
   See The Implementer's Guide [IPP-IIG] for an example.

3.1.8 Versions



   Each operation request and response carries with it a "version-
   number" parameter.  Each value of the "version-number" is in the form
   "X.Y" where X is the major version number and Y is the minor version
   number.  By including a version number in the client request, it
   allows the client  to identify which version of IPP it is interested
   in using, i.e., the version whose conformance requirements the client
   may be depending upon the Printer to meet.

   If the IPP object does not support that major version number supplied
   by the client, i.e., the major version field of the "version-number"
   parameter does not match any of the values of the Printer's "ipp-
   versions-supported" (see section 4.4.14), the object MUST respond
   with a status code of 'server-error-version-not-supported' along with
   the closest version number that is supported (see section 13.1.5.4).
   If the major version number is supported, but the minor version
   number is not, the IPP object SHOULD accept and attempt to perform
   the request (or reject the request if the operation is not
   supported), else it rejects the request and returns the 'server-
   error-version-not-supported' status code.  In all cases, the IPP
   object MUST return the "version-number" that it supports that is
   closest to the version number supplied by the client in the request.

   There is no version negotiation per se.  However, if after receiving
   a 'server-error-version-not-supported' status code from an IPP
   object, a client SHOULD try again with a different version number. A
   client MAY also determine the versions supported either from a
   directory that conforms to Appendix E (see section 16) or by querying
   the Printer object's "ipp-versions-supported" attribute (see section
   4.4.14) to determine which versions are supported.

   An IPP object implementation MUST support version '1.1', i.e., meet
   the conformance requirements for IPP/1.1 as specified in this
   document and [RFC2910].  It is recommended that IPP object
   implementations accept any request with the major version '1' (or
   reject the request if the operation is not supported).

   There is only one notion of "version number" that covers both IPP
   Model and IPP Protocol changes. Thus the version number MUST change
   when introducing a new version of the Model and Semantics document
   (this document) or a new version of the "Encoding and Transport"
   document [RFC2910].




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   Changes to the major version number of the Model and Semantics
   document indicate structural or syntactic changes that make it
   impossible for older version of IPP clients and Printer objects to
   correctly parse and correctly process the new or changed attributes,
   operations and responses.  If the major version number changes, the
   minor version numbers is set to zero.  As an example, adding the
   REQUIRED "ipp-attribute-fidelity" attribute to version '1.1' (if it
   had not been part of version '1.0'), would have required a change to
   the major version number, since an IPP/1.0 Printer would not have
   processed a request with the correct semantics that contained the
   "ipp-attribute-fidelity" attribute that it did not know about.  Items
   that might affect the changing of the major version number include
   any changes to the Model and Semantics document (this document) or
   the "Encoding and Transport" document [RFC2910] itself, such as:

      - reordering of ordered attributes or attribute sets
      - changes to the syntax of existing attributes
      - adding REQUIRED (for an IPP object to support) operation
        attribute groups
      - adding values to existing REQUIRED operation attributes
      - adding REQUIRED operations

   Changes to the minor version number indicate the addition of new
   features, attributes and attribute values that may not be understood
   by all IPP objects, but which can be ignored if not understood.
   Items that might affect the changing of the minor version number
   include any changes to the model objects and attributes but not the
   encoding and transport rules [RFC2910] (except adding attribute
   syntaxes).  Examples of such changes are:

      - grouping all extensions not included in a previous version into
        a new version
      - adding new attribute values
      - adding new object attributes
      - adding OPTIONAL (for an IPP object to support) operation
        attributes (i.e., those attributes that an IPP object can ignore
        without confusing clients)
      - adding OPTIONAL (for an IPP object to support) operation
        attribute groups (i.e., those attributes that an IPP object can
        ignore without confusing clients)
      - adding new attribute syntaxes
      - adding OPTIONAL operations
      - changing Job Description attributes or Printer Description
        attributes from OPTIONAL to REQUIRED or vice versa.
      - adding OPTIONAL attribute syntaxes to an existing attribute.

   The encoding of the "version-number" MUST NOT change over any version
   number (either major or minor).  This rule guarantees that all future



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   versions will be backwards compatible with all previous versions (at
   least for checking  the "version-number").  In addition, any protocol
   elements (attributes, error codes, tags, etc.) that are not carried
   forward from one version to the next are deprecated so that they can
   never be reused with new semantics.

   Implementations that support a certain  version NEED NOT support ALL
   previous versions.  As each new  version is defined (through the
   release of a new IPP specification document), that version will
   specify which previous  versions MUST and which versions SHOULD be
   supported in compliant implementations.

3.1.9 Job Creation Operations



   In order to "submit a print job" and create a new Job object, a
   client issues a create request.  A create request is any one of
   following three operation requests:

      - The Print-Job Request: A client that wants to submit a print job
        with only a single document uses the Print-Job operation.  The
        operation allows for the client to "push" the document data to
        the Printer object by including the document data in the request
        itself.

      - The Print-URI Request: A client that wants to submit a print job
        with only a single document (where the Printer object "pulls"
        the document data instead of the client "pushing" the data to
        the Printer object) uses the Print-URI operation.   In this
        case, the client includes in the request only a URI reference to
        the document data (not the document data itself).

      - The Create-Job Request: A client that wants to submit a print
        job with multiple documents uses the Create-Job operation.  This
        operation is followed by an arbitrary number (one or more) of
        Send-Document and/or Send-URI operations (each creating another
        document for the newly create Job object).  The Send-Document
        operation includes the document data in the request (the client
        "pushes" the document data to the printer), and the Send-URI
        operation includes only a URI reference to the document data in
        the request (the Printer "pulls" the document data from the
        referenced location).  The last Send-Document or Send-URI
        request for a given Job object includes a "last-document"
        operation attribute set to 'true' indicating that this is the
        last request.

   Throughout this model document, the term "create request" is used to
   refer to any of these three operation requests.




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   A Create-Job operation followed by only one Send-Document operation
   is semantically equivalent to a Print-Job operation, however, for
   performance reasons, the client SHOULD use the Print-Job operation
   for all single document jobs.  Also, Print-Job is a REQUIRED
   operation (all implementations MUST support it) whereas Create-Job is
   an OPTIONAL operation, hence some implementations might not support
   it.

   Job submission time is the point in time when a client issues a
   create request.  The initial state of every Job object is the
   'pending', 'pending-held', or 'processing' state (see section 4.3.7).
   When the Printer object begins processing the print job, the Job
   object's state moves to 'processing'.  This is known as job
   processing time.  There are validation checks that must be done at
   job submission time and others that must be performed at job
   processing time.

   At job submission time and at the time a Validate-Job operation is
   received, the Printer MUST do the following:

      1. Process the client supplied attributes and either accept or
         reject the request
      2. Validate the syntax of and support for the scheme of any client
         supplied URI

   At job submission time the Printer object MUST validate whether or
   not the supplied attributes, attribute syntaxes, and values are
   supported by matching them with the Printer object's corresponding
   "xxx-supported" attributes.  See section 3.1.7 for details.  [IPP-
   IIG] presents suggested steps for an IPP object to either accept or
   reject any request and additional steps for processing create
   requests.

   At job submission time the Printer object NEED NOT perform the
   validation checks reserved for job processing time such as:

      1. Validating the document data
      2. Validating the actual contents of any client supplied URI
         (resolve the reference and follow the link to the document
         data)

   At job submission time, these additional job processing time
   validation checks are essentially useless, since they require
   actually parsing and interpreting the document data, are not
   guaranteed to be 100% accurate, and MUST be done, yet again, at job
   processing time.  Also, in the case of a URI, checking for
   availability at job submission time does not guarantee availability




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   at job processing time.  In addition, at job processing time, the
   Printer object might discover any of the following conditions that
   were not detectable at job submission time:

      - runtime errors in the document data,
      - nested document data that is in an unsupported format,
      - the URI reference is no longer valid (i.e., the server hosting
        the document might be down), or
      - any other job processing error

   At job submission time, a Printer object, especially a non-spooling
   Printer, MAY accept jobs that it does not have enough space for.  In
   such a situation, a Printer object MAY stop reading data from a
   client for an indefinite period of time.  A client MUST be prepared
   for a write operation to block for an indefinite period of time (see
   section 5.1 on client conformance).

   When a Printer object has too little space for starting a new job, it
   MAY reject a new create request. In this case, a Printer object MUST
   return a response (in reply to the rejected request) with a status-
   code of 'server-error-busy' (see section 14.1.5.8) and it MAY close
   the connection before receiving all bytes of the operation.  A
   Printer SHOULD indicate that it is temporarily unable to accept jobs
   by setting the 'spool-space-full' value in its "printer-state-
   reasons" attribute and removing the value when it can accept another
   job (see section 4.4.12).

   When receiving a 'server-error-busy' status-code in an operation
   response, a client MUST be prepared for the Printer object to close
   the connection before the client has sent all of the data (especially
   for the Print-Job operation). A client MUST be prepared to keep
   submitting a create request until the IPP Printer object accepts the
   create request.

   At job processing time, since the Printer object has already
   responded with a successful status code in the response to the create
   request, if the Printer object detects an error, the Printer object
   is unable to inform the end user of the error with an operation
   status code.   In this case, the Printer, depending on the error, can
   set the job object's "job-state", "job-state-reasons", or "job-
   state-message" attributes to the appropriate value(s) so that later
   queries can report the correct job status.

   Note: Asynchronous notification of events is outside the scope of
   this IPP/1.1 document.






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3.2 Printer Operations



   All Printer operations are directed at Printer objects.  A client
   MUST always supply the "printer-uri" operation attribute in order to
   identify the correct target of the operation.

3.2.1 Print-Job Operation



   This REQUIRED operation allows a client to submit a print job with
   only one document and supply the document data (rather than just a
   reference to the data).  See Section 15 for the suggested steps for
   processing create operations and their Operation and Job Template
   attributes.

3.2.1.1 Print-Job Request



   The following groups of attributes are supplied as part of the
   Print-Job Request:

   Group 1: Operation Attributes

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.1.  The Printer object
         MUST copy these values to the corresponding Job Description
         attributes described in sections 4.3.19 and 4.3.20.

      Target:
         The "printer-uri" (uri) operation attribute which is the target
         for this operation as described in section 3.1.5.

      Requesting User Name:
         The "requesting-user-name" (name(MAX)) attribute SHOULD be
         supplied by the client as described in section 8.3.

      "job-name" (name(MAX)):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.  It contains the client
         supplied Job name.  If this attribute is supplied by the
         client, its value is used for the "job-name" attribute of the
         newly created Job object.  The client MAY automatically include
         any information that will help the end-user distinguish amongst
         his/her jobs, such as the name of the application program along
         with information from the document, such as the document name,
         document subject, or source file name.  If this attribute is
         not supplied by the client, the Printer generates a name to use
         in the "job-name" attribute of the newly created Job object
         (see Section 4.3.5).



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      "ipp-attribute-fidelity" (boolean):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.  The value 'true' indicates
         that total fidelity to client supplied Job Template attributes
         and values is required, else the Printer object MUST reject the
         Print-Job request.  The value 'false' indicates that a
         reasonable attempt to print the Job object is acceptable and
         the Printer object MUST accept the Print-Job request. If not
         supplied, the Printer object assumes the value is 'false'.  All
         Printer objects MUST support both types of job processing.  See
         section 15 for a full description of "ipp-attribute-fidelity"
         and its relationship to other attributes, especially the
         Printer object's "pdl-override-supported" attribute.

      "document-name" (name(MAX)):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.   It contains the client
         supplied document name.  The document name MAY be different
         than the Job name.  Typically, the client software
         automatically supplies the document name on behalf of the end
         user by using a file name or an application generated name.  If
         this attribute is supplied, its value can be used in a manner
         defined by each implementation.  Examples include: printed
         along with the Job (job start sheet, page adornments, etc.),
         used by accounting or resource tracking management tools, or
         even stored along with the document as a document level
         attribute.  IPP/1.1 does not support the concept of document
         level attributes.

      "compression" (type3 keyword):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute and the "compression-
         supported" attribute (see section 4.4.32).  The client supplied
         "compression" operation attribute identifies the compression
         algorithm used on the document data. The following cases exist:

         a) If the client omits this attribute, the Printer object MUST
            assume that the data is not compressed   (i.e. the Printer
            follows the rules below as if the client supplied the
            "compression" attribute with a value of 'none').
         b) If the client supplies this attribute, but the value is not
            supported by the Printer object, i.e., the value is not one
            of the values of the Printer object's "compression-
            supported" attribute, the Printer object MUST reject the
            request, and return the 'client-error-compression-not-
            supported' status code. See section 3.1.7 for returning
            unsupported attributes and values.




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         c) If the client supplies the attribute and the Printer object
            supports the attribute value, the Printer object uses the
            corresponding decompression algorithm on the document data.
         d) If the decompression algorithm fails before the Printer
            returns an operation response, the Printer object MUST
            reject the request and return the 'client-error-
            compression-error' status code.
         e) If the decompression algorithm fails after the Printer
            returns an operation response, the Printer object MUST abort
            the job and add the 'compression-error' value to the job's
            "job-state-reasons" attribute.
         f) If the decompression algorithm succeeds, the document data
            MUST then have the format specified by the job's "document-
            format" attribute, if supplied (see "document-format"
            operation attribute definition below).

      "document-format" (mimeMediaType):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.  The value of this
         attribute identifies the format of the supplied document data.
         The following cases exist:

         a) If the client does not supply this attribute, the Printer
            object assumes that the document data is in the format
            defined by the Printer object's "document-format-default"
            attribute. (i.e. the Printer follows the rules below as if
            the client supplied the "document-format" attribute with a
            value equal to the printer's default value).
         b) If the client supplies this attribute, but the value is not
            supported by the Printer object, i.e., the value is not one
            of the values of the Printer object's "document-format-
            supported" attribute, the Printer object MUST reject the
            request and return the 'client-error-document-format-not-
            supported' status code.
         c) If the client supplies this attribute and its value is
            'application/octet-stream' (i.e. to be auto-sensed, see
            Section 4.1.9.1), and the format is not one of the
            document-formats that the Printer can auto-sense, and this
            check occurs before the Printer returns an operation
            response, then the Printer MUST reject the request and
            return the  'client-error-document-format-not-supported'
            status code.
         d) If the client supplies this attribute, and the value is
            supported by the Printer object, the Printer is capable of
            interpreting the document data.






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         e) If interpreting of the document data fails before the
            Printer returns an operation response, the Printer object
            MUST reject the request and return the 'client-error-
            document-format-error' status code.
         f) If interpreting of the document data fails after the Printer
            returns an operation response, the Printer object MUST abort
            the job and add the 'document-format-error' value to the
            job's "job-state-reasons" attribute.

      "document-natural-language" (naturalLanguage):
         The client OPTIONALLY supplies this attribute.  The Printer
         object OPTIONALLY supports this attribute. This attribute
         specifies the natural language of the document for those
         document-formats that require a specification of the natural
         language in order to image the document unambiguously. There
         are no particular values required for the Printer object to
         support.

      "job-k-octets" (integer(0:MAX)):
         The client OPTIONALLY supplies this attribute.  The Printer
         object OPTIONALLY supports this attribute and the "job-k-
         octets-supported" attribute (see section 4.4.33).  The client
         supplied "job-k-octets" operation attribute identifies the
         total size of the document(s) in K octets being submitted (see
         section 4.3.17.1 for the complete semantics).  If the client
         supplies the attribute and the Printer object supports the
         attribute, the value of the attribute is used to populate the
         Job object's "job-k-octets" Job Description attribute.

         For this attribute and the following two attributes ("job-
         impressions", and "job-media-sheets"), if the client supplies
         the attribute, but the Printer object does not support the
         attribute, the Printer object ignores the client-supplied
         value.  If the client supplies the attribute and the Printer
         supports the attribute, and the value is within the range of
         the corresponding Printer object's "xxx-supported" attribute,
         the Printer object MUST use the value to populate the Job
         object's "xxx" attribute.  If the client supplies the attribute
         and the Printer supports the attribute, but the value is
         outside the range of the corresponding Printer object's "xxx-
         supported" attribute, the Printer object MUST copy the
         attribute and its value to the Unsupported Attributes response
         group, reject the request, and return the 'client-error-
         attributes-or-values-not-supported' status code.  If the client
         does not supply the attribute, the Printer object MAY choose to
         populate the corresponding Job object attribute depending on
         whether the Printer object supports the attribute and is able
         to calculate or discern the correct value.



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      "job-impressions" (integer(0:MAX)):
         The client OPTIONALLY supplies this attribute.  The Printer
         object OPTIONALLY supports this attribute and the "job-
         impressions-supported" attribute (see section 4.4.34).  The
         client supplied "job-impressions" operation attribute
         identifies the total size in number of impressions of the
         document(s) being submitted (see section 4.3.17.2 for the
         complete semantics).

         See last paragraph under "job-k-octets".

      "job-media-sheets" (integer(0:MAX)):
         The client OPTIONALLY supplies this attribute.  The Printer
         object OPTIONALLY supports this attribute and the "job-media-
         sheets-supported" attribute (see section 4.4.35).  The client
         supplied "job-media-sheets" operation attribute identifies the
         total number of media sheets to be produced for this job (see
         section 4.3.17.3 for the complete semantics).

         See last paragraph under "job-k-octets".

   Group 2: Job Template Attributes

      The client OPTIONALLY supplies a set of Job Template attributes as
      defined in section 4.2.  If the client is not supplying any Job
      Template attributes in the request, the client SHOULD omit Group 2
      rather than sending an empty group.  However, a Printer object
      MUST be able to accept an empty group.

   Group 3: Document Content

      The client MUST supply the document data to be processed.

      In addition to the MANDATORY parameters required for every
      operation request, the simplest Print-Job Request consists of just
      the "attributes-charset" and "attributes-natural-language"
      operation attributes; the "printer-uri" target operation
      attribute; the Document Content and nothing else.  In this simple
      case, the Printer object:

      - creates a new Job object (the Job object contains a single
        document),
      - stores a generated Job name in the "job-name" attribute in the
        natural language and charset requested (see Section 3.1.4.1) (if
        those are supported, otherwise using the Printer object's
        default natural language and charset), and





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      - at job processing time, uses its corresponding default value
        attributes for the supported Job Template attributes that were
        not supplied by the client as IPP attribute or embedded
        instructions in the document data.

3.2.1.2 Print-Job Response



   The Printer object MUST return to the client the following sets of
   attributes as part of the Print-Job Response:

   Group 1: Operation Attributes

      Status Message:
         In addition to the REQUIRED status code returned in every
         response, the response OPTIONALLY includes a "status-message"
         (text(255)) and/or a "detailed-status-message" (text(MAX))
         operation attribute as described in sections 13 and 3.1.6.  If
         the client supplies unsupported or conflicting Job Template
         attributes or values, the Printer object MUST reject or accept
         the Print-Job request depending on the whether the client
         supplied a 'true' or 'false' value for the "ipp-attribute-
         fidelity" operation attribute.  See the Implementer's Guide
         [IPP-IIG] for a complete description of the suggested steps for
         processing a create request.

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

      See section 3.1.7 for details on returning Unsupported Attributes.

      The value of the "ipp-attribute-fidelity" supplied by the client
      does not affect what attributes the Printer object returns in this
      group.  The value of "ipp-attribute-fidelity" only affects whether
      the Print-Job operation is accepted or rejected.  If the job is
      accepted, the client may query the job using the Get-Job-
      Attributes operation requesting the unsupported attributes that
      were returned in the create response to see which attributes were
      ignored (not stored on the Job object) and which attributes were
      stored with other (substituted) values.









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   Group 3: Job Object Attributes

      "job-uri" (uri):
         The Printer object MUST return the Job object's URI by
         returning the contents of the REQUIRED "job-uri" Job object
         attribute.  The client uses the Job object's URI when directing
         operations at the Job object.  The Printer object always uses
         its configured security policy when creating the new URI.
         However, if the Printer object supports more than one URI, the
         Printer object also uses information about which URI was used
         in the Print-Job Request to generated the new URI so that the
         new URI references the correct access channel.  In other words,
         if the Print-Job Request comes in over a secure channel, the
         Printer object MUST generate a Job URI that uses the secure
         channel as well.

      "job-id" (integer(1:MAX)):
         The Printer object MUST return the Job object's Job ID by
         returning the REQUIRED  "job-id" Job object attribute.  The
         client uses this "job-id" attribute in conjunction with the
         "printer-uri" attribute used in the Print-Job Request when
         directing Job operations at the Printer object.

      "job-state" (type1 enum):
         The Printer object MUST return the Job object's REQUIRED "job-
         state" attribute. The value of this attribute (along with the
         value of the next attribute:  "job-state-reasons") is taken
         from a "snapshot" of the new Job object at some meaningful
         point in time (implementation defined) between when the Printer
         object receives the Print-Job Request and when the Printer
         object returns the response.

      "job-state-reasons" (1setOf type2 keyword):
         The Printer object MUST return the Job object's REQUIRED "job-
         state-reasons" attribute.

      "job-state-message" (text(MAX)):
         The Printer object OPTIONALLY returns the Job object's OPTIONAL
         "job-state-message" attribute.  If the Printer object supports
         this attribute then it MUST be returned in the response.  If
         this attribute is not returned in the response, the client can
         assume that the "job-state-message" attribute is not supported
         and will not be returned in a subsequent Job object query.

      "number-of-intervening-jobs" (integer(0:MAX)):
         The Printer object OPTIONALLY returns the Job object's OPTIONAL
         "number-of-intervening-jobs" attribute.  If the Printer object
         supports this attribute then it MUST be returned in the



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         response.  If this attribute is not returned in the response,
         the client can assume that the "number-of-intervening-jobs"
         attribute is not supported and will not be returned in a
         subsequent Job object query.

         Note: Since any printer state information which affects a job's
         state is reflected in the "job-state" and "job-state-reasons"
         attributes, it is sufficient to return only these attributes
         and no specific printer status attributes.

   Note: In addition to the MANDATORY parameters required for every
   operation response, the simplest response consists of the just the
   "attributes-charset" and "attributes-natural-language" operation
   attributes and the "job-uri", "job-id", and "job-state" Job Object
   Attributes.  In this simplest case, the status code is 'successful-
   ok' and there is no "status-message" or "detailed-status-message"
   operation attribute.

3.2.2 Print-URI Operation



   This OPTIONAL operation is identical to the Print-Job operation
   (section 3.2.1) except that a client supplies a URI reference to the
   document data using the "document-uri" (uri) operation attribute (in
   Group 1) rather than including the document data itself.  Before
   returning the response, the Printer MUST validate that the Printer
   supports the retrieval method (e.g., http, ftp, etc.) implied by the
   URI, and MUST check for valid URI syntax.  If the client-supplied URI
   scheme is not supported, i.e. the value is not in the Printer
   object's "referenced-uri-scheme-supported" attribute, the Printer
   object MUST reject the request and return the 'client-error-uri-
   scheme-not-supported' status code.

   The IPP Printer MAY validate the accessibility of the document as
   part of the operation or subsequently.  If the Printer determines an
   accessibility problem before returning an operation response, it
   rejects the request and returns the 'client-error-document-access-
   error' status code.  The Printer MAY also return a specific document
   access error code using the "document-access-error" operation
   attribute (see section 3.1.6.4).

   If the Printer determines this document accessibility problem after
   accepting the request and returning an operation response with one of
   the successful status codes, the Printer adds the 'document-access-
   error' value to the job's "job-state-reasons" attribute and MAY
   populate the job's "job-document-access-errors" Job Description
   attribute (see section 4.3.11).  See The Implementer's Guide [IPP-
   IIG] for suggested additional checks.




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   If the Printer object supports this operation, it MUST support the
   "reference-uri-schemes-supported" Printer attribute (see section
   4.4.27).

   It is up to the IPP object to interpret the URI and subsequently
   "pull" the document from the source referenced by the URI string.

3.2.3 Validate-Job Operation



   This REQUIRED operation is similar to the Print-Job operation
   (section 3.2.1) except that a client supplies no document data and
   the Printer allocates no resources (i.e., it does not create a new
   Job object).  This operation is used only to verify capabilities of a
   printer object against whatever attributes are supplied by the client
   in the Validate-Job request.  By using the Validate-Job operation a
   client can validate that an identical Print-Job operation (with the
   document data) would be accepted. The Validate-Job operation also
   performs the same security negotiation as the Print-Job operation
   (see section 8), so that a client can check that the client and
   Printer object security requirements can be met before performing a
   Print-Job operation.

   The Validate-Job operation does not accept a "document-uri" attribute
   in order to allow a client to check that the same Print-URI operation
   will be accepted, since the client doesn't send the data with the
   Print-URI operation.  The client SHOULD just issue the Print-URI
   request.

   The Printer object returns the same status codes, Operation
   Attributes (Group 1) and Unsupported Attributes (Group 2) as the
   Print-Job operation.  However, no Job Object Attributes (Group 3) are
   returned, since no Job object is created.

3.2.4 Create-Job Operation



   This OPTIONAL operation is similar to the Print-Job operation
   (section 3.2.1) except that in the Create-Job request, a client does
   not supply document data or any reference to document data.  Also,
   the client does not supply any of the "document-name", "document-
   format", "compression", or "document-natural-language" operation
   attributes.  This operation is followed by one or more Send-Document
   or Send-URI operations.  In each of those operation requests, the
   client OPTIONALLY supplies the "document-name", "document-format",
   and "document-natural-language" attributes for each document in the
   multi-document Job object.






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   If a Printer object supports the Create-Job operation, it MUST also
   support the Send-Document operation and also MAY support the Send-URI
   operation.

   If the Printer object supports this operation, it MUST support the
   "multiple-operation-time-out" Printer attribute (see section 4.4.31).

   If the Printer object supports this operation, then it MUST support
   the "multiple-document-jobs-supported" Printer Description attribute
   (see section 4.4.16) and indicate whether or not it supports
   multiple-document jobs.

   If the Printer object supports this operation and supports multiple
   documents in a job, then it MUST support the "multiple-document-
   handling" Job Template job attribute with at least one value (see
   section 4.2.4) and the associated "multiple-document-handling-
   default" and "multiple-document-handling-supported" Job Template
   Printer attributes (see section 4.2).

   After the Create-Job operation has completed, the value of the "job-
   state" attribute is similar to the "job-state" after a Print-Job,
   even though no document-data has arrived.  A Printer MAY set the
   'job-data-insufficient' value of the job's "job-state-reason"
   attribute to indicate that processing cannot begin until sufficient
   data has arrived and set the "job-state" to either 'pending' or
   'pending-held'.  A non-spooling printer that doesn't implement the
   'pending' job state may even set the "job-state" to 'processing',
   even though there is not yet any data to process.  See sections 4.3.7
   and 4.3.8.

3.2.5 Get-Printer-Attributes Operation



   This REQUIRED operation allows a client to request the values of the
   attributes of a Printer object.   In the request, the client supplies
   the set of Printer attribute names and/or attribute group names in
   which the requester is interested.  In the response, the Printer
   object returns a corresponding attribute set with the appropriate
   attribute values filled in.

   For Printer objects, the possible names of attribute groups are:

      - 'job-template': the subset of the Job Template attributes that
        apply to a Printer object (the last two columns of the table in
        Section 4.2) that the implementation supports for Printer
        objects.
      - 'printer-description': the subset of the attributes specified in
        Section 4.4 that the implementation supports for Printer
        objects.



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      - 'all': the special group 'all' that includes all attributes that
        the implementation supports for Printer objects.

   Since a client MAY request specific attributes or named groups, there
   is a potential that there is some overlap.  For example, if a client
   requests, 'printer-name' and 'all', the client is actually requesting
   the "printer-name" attribute twice: once by naming it explicitly, and
   once by inclusion in the 'all' group.  In such cases, the Printer
   object NEED NOT return each attribute only once in the response even
   if it is requested multiple times.  The client SHOULD NOT request the
   same attribute in multiple ways.

   It is NOT REQUIRED that a Printer object support all attributes
   belonging to a group (since some attributes are OPTIONAL).  However,
   it is REQUIRED that each Printer object support all group names.

3.2.5.1 Get-Printer-Attributes Request



   The following sets of attributes are part of the Get-Printer-
   Attributes Request:

   Group 1: Operation Attributes

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.1.

      Target:
         The "printer-uri" (uri) operation attribute which is the target
         for this operation as described in section 3.1.5.

      Requesting User Name:
         The "requesting-user-name" (name(MAX)) attribute SHOULD be
         supplied by the client as described in section 8.3.

      "requested-attributes" (1setOf keyword):
         The client OPTIONALLY supplies a set of attribute names and/or
         attribute group names in whose values the requester is
         interested.  The Printer object MUST support this attribute.
         If the client omits this attribute, the Printer MUST respond as
         if this attribute had been supplied with a value of 'all'.

      "document-format" (mimeMediaType):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.  This attribute is useful
         for a Printer object to determine the set of supported
         attribute values that relate to the requested document format.
         The Printer object MUST return the attributes and values that



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         it uses to validate a job on a create or Validate-Job operation
         in which this document format is supplied. The Printer object
         SHOULD return only (1) those attributes that are supported for
         the specified format and (2) the attribute values that are
         supported for the specified document format.  By specifying the
         document format, the client can get the Printer object to
         eliminate the attributes and values that are not supported for
         a specific document format.  For example, a Printer object
         might have multiple interpreters to support both
         'application/postscript' (for PostScript) and 'text/plain' (for
         text) documents.  However, for only one of those interpreters
         might the Printer object be able to support "number-up" with
         values of '1', '2', and '4'.  For the other interpreter it
         might be able to only support "number-up" with a value of '1'.
         Thus a client can use the Get-Printer-Attributes operation to
         obtain the attributes and values that will be used to
         accept/reject a create job operation.

         If the Printer object does not distinguish between different
         sets of supported values for each different document format
         when validating jobs in the create and Validate-Job operations,
         it MUST NOT distinguish between different document formats in
         the Get-Printer-Attributes operation. If the Printer object
         does distinguish between different sets of supported values for
         each different document format specified by the client, this
         specialization applies only to the following Printer object
         attributes:

      - Printer attributes that are Job Template attributes ("xxx-
        default" "xxx-supported", and "xxx-ready" in the Table in
        Section 4.2),
      - "pdl-override-supported",
      - "compression-supported",
      - "job-k-octets-supported",
      - "job-impressions-supported",
      - "job-media-sheets-supported",
      - "printer-driver-installer",
      - "color-supported", and
      - "reference-uri-schemes-supported"

      The values of all other Printer object attributes (including
      "document-format-supported") remain invariant with respect to the
      client supplied document format (except for new Printer
      description attribute as registered according to section 6.2).

      If the client omits this "document-format" operation attribute,
      the Printer object MUST respond as if the attribute had been
      supplied with the value of the Printer object's "document-format-



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      default" attribute.  It is RECOMMENDED that the client always
      supply a value for "document-format", since the Printer object's
      "document-format-default" may be 'application/octet-stream', in
      which case the returned attributes and values are for the union of
      the document formats that the Printer can automatically sense.
      For more details, see the description of the 'mimeMediaType'
      attribute syntax in section 4.1.9.

      If the client supplies a value for the "document-format" Operation
      attribute that is not supported by the Printer, i.e., is not among
      the values of the Printer object's "document-format-supported"
      attribute, the Printer object MUST reject the operation and return
      the 'client-error-document-format-not-supported' status code.

3.2.5.2 Get-Printer-Attributes Response



   The Printer object returns the following sets of attributes as part
   of the Get-Printer-Attributes Response:

   Group 1: Operation Attributes

      Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text(255)) and/or a "detailed-status-message" (text(MAX))
        operation attribute as described in sections 13 and  3.1.6.

      Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

      See section 3.1.7 for details on returning Unsupported Attributes.

      The response NEED NOT contain the "requested-attributes" operation
      attribute with any supplied values (attribute keywords) that were
      requested by the client but are not supported by the IPP object.
      If the Printer object does return unsupported attributes
      referenced in the "requested-attributes" operation attribute and
      that attribute included group names, such as 'all', the
      unsupported attributes MUST NOT include attributes described in
      the standard but not supported by the implementation.








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   Group 3: Printer Object Attributes

      This is the set of requested attributes and their current values.
      The Printer object ignores (does not respond with) any requested
      attribute which is not supported.  The Printer object MAY respond
      with a subset of the supported attributes and values, depending on
      the security policy in force.  However, the Printer object MUST
      respond with the 'unknown' value for any supported attribute
      (including all REQUIRED attributes) for which the Printer object
      does not know the value.  Also the Printer object MUST respond
      with the 'no-value' for any supported attribute (including all
      REQUIRED attributes) for which the system administrator has not
      configured a value.  See the description of the "out-of-band"
      values in the beginning of Section 4.1.

3.2.6 Get-Jobs Operation



   This REQUIRED operation allows a client to retrieve the list of Job
   objects belonging to the target Printer object.  The client may also
   supply a list of Job attribute names and/or attribute group names.  A
   group of Job object attributes will be returned for each Job object
   that is returned.

   This operation is similar to the Get-Job-Attributes operation, except
   that this Get-Jobs operation returns attributes from possibly more
   than one object.

3.2.6.1 Get-Jobs Request



   The client submits the Get-Jobs request to a Printer object.

   The following groups of attributes are part of the Get-Jobs Request:

   Group 1: Operation Attributes

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.1.

      Target:
         The "printer-uri" (uri) operation attribute which is the target
         for this operation as described in section 3.1.5.

      Requesting User Name:
         The "requesting-user-name" (name(MAX)) attribute SHOULD be
         supplied by the client as described in section 8.3.





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      "limit" (integer(1:MAX)):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute. It is an integer value that
         determines the maximum number of jobs that a client will
         receive from the Printer even if "which-jobs" or "my-jobs"
         constrain which jobs are returned.  The limit is a "stateless
         limit" in that if the value supplied by the client is 'N', then
         only the first 'N' jobs are returned in the Get-Jobs Response.
         There is no mechanism to allow for the next 'M' jobs after the
         first 'N' jobs.  If the client does not supply this attribute,
         the Printer object responds with all applicable jobs.

      "requested-attributes" (1setOf type2 keyword):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.  It is a set of Job
         attribute names and/or attribute groups names in whose values
         the requester is interested.  This set of attributes is
         returned for each Job object that is returned.  The allowed
         attribute group names are the same as those defined in the
         Get-Job-Attributes operation in section 3.3.4.  If the client
         does not supply this attribute, the Printer MUST respond as if
         the client had supplied this attribute with two values: 'job-
         uri' and 'job-id'.

      "which-jobs" (type2 keyword):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.  It indicates which Job
         objects MUST be returned by the Printer object. The values for
         this attribute are:

      'completed': This includes any Job object whose state is
         'completed', 'canceled', or 'aborted'.
      'not-completed': This includes any Job object whose state is
         'pending', 'processing', 'processing-stopped', or 'pending-
         held'.

         A Printer object MUST support both values.  However, if the
         implementation does not keep jobs in the 'completed',
         'canceled', and 'aborted' states, then it returns no jobs when
         the 'completed' value is supplied.

         If a client supplies some other value, the Printer object MUST
         copy the attribute and the unsupported value to the Unsupported
         Attributes response group, reject the request, and return the
         'client-error-attributes-or-values-not-supported' status code.






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         If the client does not supply this attribute, the Printer
         object MUST respond as if the client had supplied the attribute
         with a value of 'not-completed'.

      "my-jobs" (boolean):
         The client OPTIONALLY supplies this attribute.  The Printer
         object MUST support this attribute.  It indicates whether jobs
         from all users or just the jobs submitted by the requesting
         user of this request MUST be considered as candidate jobs to be
         returned by the Printer object.  If the client does not supply
         this attribute, the Printer object MUST respond as if the
         client had supplied the attribute with a value of 'false',
         i.e., jobs from all users.  The means for authenticating the
         requesting user and matching the jobs is described in section
         8.

3.2.6.2 Get-Jobs Response



   The Printer object returns all of the Job objects up to the number
   specified by the "limit" attribute that match the criteria as defined
   by the attribute values supplied by the client in the request.  It is
   possible that no Job objects are returned since there may literally
   be no Job objects at the Printer, or there may be no Job objects that
   match the criteria supplied by the client.  If the client requests
   any Job attributes at all, there is a set of Job Object Attributes
   returned for each Job object.

   It is not an error for the Printer to return 0 jobs. If the response
   returns 0 jobs because there are no jobs matching the criteria, and
   the request would have returned 1 or more jobs with a status code of
   'successful-ok' if there had been jobs matching the criteria, then
   the status code for 0 jobs MUST be 'successful-ok'.

   Group 1: Operation Attributes

      Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text(255)) and/or a "detailed-status-message" (text(MAX))
        operation attribute as described in sections 13 and 3.1.6.

      Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.







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   Group 2: Unsupported Attributes

      See section 3.1.7 for details on returning Unsupported Attributes.

      The response NEED NOT contain the "requested-attributes" operation
      attribute with any supplied values (attribute keywords) that were
      requested by the client but are not supported by the IPP object.
      If the Printer object does return unsupported attributes
      referenced in the "requested-attributes" operation attribute and
      that attribute included group names, such as 'all', the
      unsupported attributes MUST NOT include attributes described in
      the standard but not supported by the implementation.

   Groups 3 to N: Job Object Attributes

      The Printer object responds with one set of Job Object Attributes
      for each returned Job object.  The Printer object ignores (does
      not respond with) any requested attribute or value which is not
      supported or which is restricted by the security policy in force,
      including whether the requesting user is the user that submitted
      the job (job originating user) or not (see section 8).  However,
      the Printer object MUST respond with the 'unknown' value for any
      supported attribute (including all REQUIRED attributes) for which
      the Printer object does not know the value, unless it would
      violate the security policy.  See the description of the "out-of-
      band" values in the beginning of Section 4.1.

      Jobs are returned in the following order:

      - If the client requests all 'completed' Jobs (Jobs in the
        'completed', 'aborted', or 'canceled' states), then the Jobs are
        returned newest to oldest (with respect to actual completion
        time)
      - If the client requests all 'not-completed' Jobs (Jobs in the
        'pending', 'processing', 'pending-held', and 'processing-
        stopped' states), then Jobs are returned in relative
        chronological order of expected time to complete (based on
        whatever scheduling algorithm is configured for the Printer
        object).

3.2.7 Pause-Printer Operation



   This OPTIONAL operation allows a client to stop the Printer object
   from scheduling jobs on all its devices.  Depending on
   implementation, the Pause-Printer operation MAY also stop the Printer
   from processing the current job or jobs.  Any job that is currently
   being printed is either stopped as soon as the implementation permits




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   or is completed, depending on implementation.  The Printer object
   MUST still accept create operations to create new jobs, but MUST
   prevent any jobs from entering the 'processing' state.

   If the Pause-Printer operation is supported, then the Resume-Printer
   operation MUST be supported, and vice-versa.

   The IPP Printer stops the current job(s) on its device(s) that were
   in the 'processing' or 'processing-stopped' states as soon as the
   implementation permits.  If the implementation will take appreciable
   time to stop, the IPP Printer adds the 'moving-to-paused' value to
   the Printer object's "printer-state-reasons" attribute (see section
   4.4.12).  When the device(s) have all stopped, the IPP Printer
   transitions the Printer object to the 'stopped' state, removes the
   'moving-to-paused' value, if present, and adds the 'paused' value to
   the Printer object's "printer-state-reasons" attribute.

   When the current job(s) complete that were in the 'processing' state,
   the IPP Printer transitions them to the 'completed' state.  When the
   current job(s) stop in mid processing that were in the 'processing'
   state, the IPP Printer transitions them to the 'processing-stopped'
   state and adds the 'printer-stopped' value to the job's "job-state-
   reasons" attribute.

   For any jobs that are 'pending' or 'pending-held', the 'printer-
   stopped' value of the jobs' "job-state-reasons" attribute also
   applies.  However, the IPP Printer NEED NOT update those jobs' "job-
   state-reasons" attributes and only need return the 'printer-stopped'
   value when those jobs are queried (so-called "lazy evaluation").

   Whether the Pause-Printer operation affects jobs that were submitted
   to the device from other sources than the IPP Printer object in the
   same way that the Pause-Printer operation affects jobs that were
   submitted to the IPP Printer object using IPP, depends on
   implementation, i.e., on whether the IPP protocol is being used as a
   universal management protocol or just to manage IPP jobs,
   respectively.

   The IPP Printer MUST accept the request in any state and transition
   the Printer to the indicated new "printer-state" before returning as
   follows:










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     Current        New      "printer   IPP Printer's response status
    "printer-    "printer-   -state-          code and action:
     state"       state"    reasons"

  'idle'       'stopped'    'paused'  'successful-ok'
  'processing' 'processing' 'moving-  OPTION 1: 'successful-ok';
                              to-       Later, when all output has
                              paused'   stopped, the "printer-state"
                                        becomes 'stopped', and the
                                        'paused' value replaces the
                                        'moving-to-paused' value in the
                                        "printer-state-reasons"
                                        attribute
  'processing' 'stopped'    'paused'  OPTION 2: 'successful-ok';
                                        all device output stopped
                                        immediately
  'stopped'    'stopped'    'paused'  'successful-ok'

   Access Rights: The authenticated user (see section 8.3) performing
   this operation must be an operator or administrator of the Printer
   object (see Sections 1 and 8.5).   Otherwise, the IPP Printer MUST
   reject the operation and return:  'client-error-forbidden', 'client-
   error-not-authenticated', or 'client-error-not-authorized' as
   appropriate.

3.2.7.1 Pause-Printer Request



   The following groups of attributes are part of the Pause-Printer
   Request:

   Group 1: Operation Attributes

      Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.

      Target:
        The "printer-uri" (uri) operation attribute which is the target
        for this operation as described in section 3.1.5.

      Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.








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3.2.7.2 Pause-Printer Response



   The following groups of attributes are part of the Pause-Printer
   Response:

   Group 1: Operation Attributes

      Status Message:
        In addition to the REQUIRED status code returned in every
        response, the response OPTIONALLY includes a "status-message"
        (text(255)) and/or a "detailed-status-message" (text(MAX))
        operation attribute as described in sections 13 and  3.1.6.

      Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

      See section 3.1.7 for details on returning Unsupported Attributes.

3.2.8 Resume-Printer Operation



   This operation allows a client to resume the Printer object
   scheduling jobs on all its devices.  The Printer object MUST remove
   the 'paused' and 'moving-to-paused' values from the Printer object's
   "printer-state-reasons" attribute, if present.  If there are no other
   reasons to keep a device paused (such as media-jam), the IPP Printer
   is free to transition itself to the 'processing' or 'idle' states,
   depending on whether there are jobs to be processed or not,
   respectively, and the device(s) resume processing jobs.

   If the Pause-Printer operation is supported, then the Resume-Printer
   operation MUST be supported, and vice-versa.

   The IPP Printer removes the 'printer-stopped' value from any job's
   "job-state-reasons" attributes contained in that Printer.

   The IPP Printer MUST accept the request in any state, transition the
   Printer object to the indicated new state as follows:











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     Current    New "printer-  IPP Printer's response status code and
    "printer-      state"                     action:
      state"

   'idle'       'idle'         'successful-ok'
   'processing' 'processing'   'successful-ok'

   'stopped'    'processing'   'successful-ok';
                               when there are jobs to be processed
   'stopped'    'idle'         'successful-ok';
                               when there are no jobs to be processed.

   Access Rights: The authenticated user (see section 8.3) performing
   this operation must be an operator or administrator of the Printer
   object (see Sections 1 and 8.5).  Otherwise, the IPP Printer MUST
   reject the operation and return:  'client-error-forbidden', 'client-
   error-not-authenticated', or 'client-error-not-authorized' as
   appropriate.

   The Resume-Printer Request and Resume-Printer Response have the same
   attribute groups and attributes as the Pause-Printer operation (see
   sections 3.2.7.1 and 3.2.7.2).

3.2.9 Purge-Jobs Operation



   This OPTIONAL operation allows a client to remove all jobs from an
   IPP Printer object, regardless of their job states, including jobs in
   the Printer object's Job History (see Section 4.3.7.2).  After a
   Purge-Jobs operation has been performed, a Printer object MUST return
   no jobs in subsequent Get-Job-Attributes and Get-Jobs responses
   (until new jobs are submitted).

   Whether the Purge-Jobs (and Get-Jobs) operation affects jobs that
   were submitted to the device from other sources than the IPP Printer
   object in the same way that the Purge-Jobs operation affects jobs
   that were submitted to the IPP Printer object using IPP, depends on
   implementation, i.e., on whether the IPP protocol is being used as a
   universal management protocol or just to manage IPP jobs,
   respectively.

   Note:  if an operator wants to cancel all jobs without clearing out
   the Job History, the operator uses the Cancel-Job operation on each
   job instead of using the Purge-Jobs operation.

   The Printer object MUST accept this operation in any state and
   transition the Printer object to the 'idle' state.





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   Access Rights: The authenticated user (see section 8.3) performing
   this operation must be an operator or administrator of the Printer
   object (see Sections 1 and 8.5).  Otherwise, the IPP object MUST
   reject the operation and return: client-error-forbidden, client-
   error-not-authenticated, and client-error-not-authorized as
   appropriate.

   The Purge-Jobs Request and Purge-Jobs Response have the same
   attribute groups and attributes as the Pause-Printer operation (see
   sections 3.2.7.1 and 3.2.7.2).

3.3 Job Operations



   All Job operations are directed at Job objects.  A client MUST always
   supply some means of identifying the Job object in order to identify
   the correct target of the operation.  That job identification MAY
   either be a single Job URI or a combination of a Printer URI with a
   Job ID.  The IPP object implementation MUST support both forms of
   identification for every job.

3.3.1 Send-Document Operation



   This OPTIONAL operation allows a client to create a multi-document
   Job object that is initially "empty" (contains no documents).  In the
   Create-Job response, the Printer object returns the Job object's URI
   (the "job-uri" attribute) and the Job object's 32-bit identifier (the
   "job-id" attribute).  For each new document that the client desires
   to add, the client uses a Send-Document operation.  Each Send-
   Document Request contains the entire stream of document data for one
   document.

   If the Printer supports this operation but does not support multiple
   documents per job, the Printer MUST reject subsequent Send-Document
   operations supplied with data and return the 'server-error-multiple-
   document-jobs-not-supported'.  However, the Printer MUST accept the
   first document with a 'true' or 'false' value for the "last-document"
   operation attribute (see below), so that clients MAY always submit
   one document jobs with a 'false' value for "last-document" in the
   first Send-Document and a 'true' for "last-document" in the second
   Send-Document (with no data).

   Since the Create-Job and the send operations (Send-Document or Send-
   URI operations) that follow could occur over an arbitrarily long
   period of time for a particular job, a client MUST send another send
   operation within an IPP Printer defined minimum time interval after
   the receipt of the previous request for the job.  If a Printer object
   supports the Create-Job and Send-Document operations, the Printer
   object MUST support the "multiple-operation-time-out" attribute (see



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   section 4.4.31).  This attribute indicates the minimum number of
   seconds the Printer object will wait for the next send operation
   before taking some recovery action.

   An IPP object MUST recover from an errant client that does not supply
   a send operation, sometime after the minimum time interval specified
   by the Printer object's "multiple-operation-time-out" attribute.
   Such recovery MAY include any of the following or other recovery
   actions:

      1. Assume that the Job is an invalid job, start the process of
         changing the job state to 'aborted', add the 'aborted-by-
         system' value to the job's "job-state-reasons" attribute (see
         section 4.3.8), and clean up all resources associated with the
         Job.  In this case, if another send operation is finally
         received, the Printer responds with an "client-error-not-
         possible" or "client-error-not-found" depending on whether or
         not the Job object is still around when the send operation
         finally arrives.
      2. Assume that the last send operation received was in fact the
         last document (as if the "last-document" flag had been set to
         'true'), close the Job object, and proceed to process it (i.e.,
         move the Job's state to 'pending').
      3. Assume that the last send operation received was in fact the
         last document, close the Job, but move it to the 'pending-held'
         and add the 'submission-interrupted' value to the job's "job-
         state-reasons" attribute (see section 4.3.8).  This action
         allows the user or an operator to determine whether to continue
         processing the Job by moving it back to the 'pending' state
         using the Release-Job operation (see section 3.3.6) or to
         cancel the job using the Cancel-Job operation (see section
         3.3.3).

   Each implementation is free to decide the "best" action to take
   depending on local policy, whether any documents have been added,
   whether the implementation spools jobs or not,  and/or any other
   piece of information available to it.  If the choice is to abort the
   Job object, it is possible that the Job object may already have been
   processed to the point that some media sheet pages have been printed.

   Access Rights: The authenticated user (see section 8.3) performing
   this operation must either be the job owner (as determined in the
   Create-Job operation) or an operator or administrator of the Printer
   object (see Sections 1 and 8.5).  Otherwise, the IPP object MUST
   reject the operation and return: 'client-error-forbidden', 'client-
   error-not-authenticated', or 'client-error-not-authorized' as
   appropriate.




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3.3.1.1 Send-Document Request



   The following attribute sets are part of the Send-Document Request:

   Group 1: Operation Attributes

      Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.

      Target:
        Either (1) the "printer-uri" (uri) plus "job-id"
        (integer(1:MAX))or (2) the "job-uri" (uri) operation
        attribute(s) which define the target for this operation as
        described in section 3.1.5.

      Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.

      "document-name" (name(MAX)):
        The client OPTIONALLY supplies this attribute.  The Printer
        object MUST support this attribute.  It contains the client
        supplied document name.  The document name MAY be different than
        the Job name.  It might be helpful, but NEED NOT be unique
        across multiple documents in the same Job.  Typically, the
        client software automatically supplies the document name on
        behalf of the end user by using a file name or an application
        generated name.  See the description of the "document-name"
        operation attribute in the Print-Job Request (section 3.2.1.1)
        for more information about this attribute.

      "compression" (type3 keyword):
        See the description of "compression" for the Print-Job operation
        in Section 3.2.1.1.

      "document-format" (mimeMediaType):
        See the description of "document-format" for the Print-Job
        operation in Section 3.2.1.1.

      "document-natural-language" (naturalLanguage):
        The client OPTIONALLY supplies this attribute.  The Printer
        object OPTIONALLY supports this attribute.  This attribute
        specifies the natural language of the document for those
        document-formats that require a specification of the natural
        language in order to image the document unambiguously.  There
        are no particular values required for the Printer object to
        support.



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      "last-document" (boolean):
        The client MUST supply this attribute.  The Printer object MUST
        support this attribute. It is a boolean flag that is set to
        'true' if this is the last document for the Job, 'false'
        otherwise.

   Group 2: Document Content

      The client MUST supply the document data if the "last-document"
      flag is set to 'false'.  However, since a client might not know
      that the previous document sent with a Send-Document (or Send-URI)
      operation was the last document (i.e., the "last-document"
      attribute was set to 'false'), it is legal to send a Send-Document
      request with no document data where the "last-document" flag is
      set to 'true'.  Such a request MUST NOT increment the value of the
      Job object's "number-of-documents" attribute, since no real
      document was added to the job.  It is not an error for a client to
      submit a job with no actual document data, i.e., only a single
      Create-Job and Send-Document request with a "last-document"
      operation attribute set to 'true' with no document data.

3.3.1.2 Send-Document Response



   The following sets of attributes are part of the Send-Document
   Response:

   Group 1: Operation Attributes

      Status Message:
         In addition to the REQUIRED status code returned in every
         response, the response OPTIONALLY includes a "status-message"
         (text(255)) and/or a "detailed-status-message" (text(MAX))
         operation attribute as described in sections 13 and 3.1.6.

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

      See section 3.1.7 for details on returning Unsupported Attributes.

   Group 3: Job Object Attributes

      This is the same set of attributes as described in the Print-Job
      response (see section 3.2.1.2).





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3.3.2 Send-URI Operation



   This OPTIONAL operation is identical to the Send-Document operation
   (see section 3.3.1) except that a client MUST supply a URI reference
   ("document-uri" operation attribute) rather than the document data
   itself.  If a Printer object supports this operation, clients can use
   both Send-URI or Send-Document operations to add new documents to an
   existing multi-document Job object.  However, if a client needs to
   indicate that the previous Send-URI or Send-Document was the last
   document,  the client MUST use the Send-Document operation with no
   document data and the "last-document" flag set to 'true' (rather than
   using a Send-URI operation with no "document-uri" operation
   attribute).

   If a Printer object supports this operation, it MUST also support the
   Print-URI operation (see section 3.2.2).

   The Printer object MUST validate the syntax and URI scheme of the
   supplied URI before returning a response, just as in the Print-URI
   operation.  The IPP Printer MAY validate the accessibility of the
   document as part of the operation or subsequently (see section
   3.2.2).

3.3.3 Cancel-Job Operation



   This REQUIRED operation allows a client to cancel a Print Job from
   the time the job is created up to the time it is completed, canceled,
   or aborted.  Since a Job might already be printing by the time a
   Cancel-Job is received, some media sheet pages might be printed
   before the job is actually terminated.

   The IPP object MUST accept or reject the request based on the job's
   current state and transition the job to the indicated new state as
   follows:

















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       Current "job-    New "job-     IPP object's response status
           state"         state"             code and action:

      'pending'       'canceled'     'successful-ok'
      'pending-held'  'canceled'     'successful-ok'
      'processing'    'canceled'     'successful-ok'
      'processing'    'processing'   'successful-ok'  See Rule 1
      'processing'    'processing'   'client-error-not-possible'
                                     See Rule 2
      'processing-    'canceled'     'successful-ok'
      stopped'
      'processing-    'processing-   'successful-ok'  See Rule 1
      stopped'        stopped'
      'processing-    'processing-   'client-error-not-possible'
      stopped'        stopped'       See Rule 2
      'completed'     'completed'    'client-error-not-possible'
      'canceled'      'canceled'     'client-error-not-possible'
      'aborted'       'aborted'      'client-error-not-possible'

   Rule 1:  If the implementation requires some measurable time to
   cancel the job in the 'processing' or 'processing-stopped' job
   states, the IPP object MUST add the 'processing-to-stop-point' value
   to the job's "job-state-reasons" attribute and then transition the
   job to the 'canceled' state when the processing ceases (see section
   4.3.8).

   Rule 2:  If the Job object already has the 'processing-to-stop-point'
   value in its "job-state-reasons" attribute, then the Printer object
   MUST reject a Cancel-Job operation.

   Access Rights: The authenticated user (see section 8.3) performing
   this operation must either be the job owner or an operator or
   administrator of the Printer object (see Sections 1 and 8.5).
   Otherwise, the IPP object MUST reject the operation and return:
    'client-error-forbidden', 'client-error-not-authenticated', or
   'client-error-not-authorized' as appropriate.

3.3.3.1 Cancel-Job Request



   The following groups of attributes are part of the Cancel-Job
   Request:

   Group 1: Operation Attributes

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.1.




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      Target:
         Either (1) the "printer-uri" (uri) plus "job-id"
         (integer(1:MAX))or (2) the "job-uri" (uri) operation
         attribute(s) which define the target for this operation as
         described in section 3.1.5.

      Requesting User Name:
         The "requesting-user-name" (name(MAX)) attribute SHOULD be
         supplied by the client as described in section 8.3.

      "message" (text(127)):
         The client OPTIONALLY supplies this attribute.  The Printer
         object OPTIONALLY supports this attribute. It is a message to
         the operator.  This "message" attribute is not the same as the
         "job-message-from-operator" attribute.  That attribute is used
         to report a message from the operator to the end user that
         queries that attribute.  This "message" operation attribute is
         used to send a message from the client to the operator along
         with the operation request.  It is an implementation decision
         of how or where to display this message to the operator (if at
         all).

3.3.3.2 Cancel-Job Response



   The following sets of attributes are part of the Cancel-Job Response:

   Group 1: Operation Attributes

      Status Message:
         In addition to the REQUIRED status code returned in every
         response, the response OPTIONALLY includes a "status-message"
         (text(255)) and/or a "detailed-status-message" (text(MAX))
         operation attribute as described in sections 13 and 3.1.6.

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.2.

   Group 2: Unsupported Attributes

      See section 3.1.7 for details on returning Unsupported Attributes.

   Once a successful response has been sent, the implementation
   guarantees that the Job will eventually end up in the 'canceled'
   state. Between the time of the Cancel-Job operation is accepted and
   when the job enters the 'canceled' job-state (see section 4.3.7), the
   "job-state-reasons" attribute SHOULD contain the 'processing-to-
   stop-point'



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   value which indicates to later queries that although the Job might
   still be 'processing', it will eventually end up in the
   'canceled' state, not the 'completed' state.

3.3.4 Get-Job-Attributes Operation



   This REQUIRED operation allows a client to request the values of
   attributes of a Job object and it is almost identical to the Get-
   Printer-Attributes operation (see section 3.2.5).  The only
   differences are that the operation is directed at a Job object rather
   than a Printer object, there is no "document-format" operation
   attribute used when querying a Job object, and the returned attribute
   group is a set of Job object attributes rather than a set of Printer
   object attributes.

   For Jobs, the possible names of attribute groups are:

      - 'job-template': the subset of the Job Template attributes that
        apply to a Job object (the first column of the table in Section
        4.2) that the implementation supports for Job objects.
      - 'job-description': the subset of the Job Description attributes
        specified in Section 4.3 that the implementation supports for
        Job objects.
      - 'all': the special group 'all' that includes all attributes that
        the implementation supports for Job objects.

   Since a client MAY request specific attributes or named groups, there
   is a potential that there is some overlap.  For example, if a client
   requests, 'job-name' and 'job-description', the client is actually
   requesting the "job-name" attribute once by naming it explicitly, and
   once by inclusion in the 'job-description' group.  In such cases, the
   Printer object NEED NOT return the attribute only once in the
   response even if it is requested multiple times.  The client SHOULD
   NOT
request the same attribute in multiple ways.

   It is NOT REQUIRED that a Job object support all attributes belonging
   to a group (since some attributes are OPTIONAL).  However it is
   REQUIRED that each Job object support all these group names.

3.3.4.1 Get-Job-Attributes Request



   The following groups of attributes are part of the Get-Job-Attributes
   Request when the request is directed at a Job object:








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   Group 1: Operation Attributes

      Natural Language and Character Set:
        The "attributes-charset" and "attributes-natural-language"
        attributes as described in section 3.1.4.1.

      Target:
        Either (1) the "printer-uri" (uri) plus "job-id"
        (integer(1:MAX)) or (2) the "job-uri" (uri) operation
        attribute(s) which define the target for this operation as
        described in section 3.1.5.

      Requesting User Name:
        The "requesting-user-name" (name(MAX)) attribute SHOULD be
        supplied by the client as described in section 8.3.

      "requested-attributes" (1setOf keyword):
        The client OPTIONALLY supplies this attribute.  The IPP object
        MUST support this attribute.   It is a set of attribute names
        and/or attribute group names in whose values the requester is
        interested.  If the client omits this attribute, the IPP object
        MUST respond as if this attribute had been supplied with a value
        of 'all'.

3.3.4.2 Get-Job-Attributes Response



   The Printer object returns the following sets of attributes as part
   of the Get-Job-Attributes Response:

   Group 1: Operation Attributes

      Status Message:
         In addition to the REQUIRED status code returned in every
         response, the response OPTIONALLY includes a "status-message"
         (text(255)) and/or a "detailed-status-message" (text(MAX))
         operation attribute as described in sections 13 and 3.1.6.

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as described in section 3.1.4.2.  The "attributes-
         natural-language" MAY be the natural language of the Job
         object, rather than the one requested.

   Group 2: Unsupported Attributes

      See section 3.1.7 for details on returning Unsupported Attributes.





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      The response NEED NOT contain the "requested-attributes" operation
      attribute with any supplied values (attribute keywords) that were
      requested by the client but are not supported by the IPP object.
      If the Printer object does return unsupported attributes
      referenced in the "requested-attributes" operation attribute and
      that attribute included group names, such as 'all', the
      unsupported attributes MUST NOT include attributes described in
      the standard but not supported by the implementation.

   Group 3: Job Object Attributes

      This is the set of requested attributes and their current values.
      The IPP object ignores (does not respond with) any requested
      attribute or value which is not supported or which is restricted
      by the security policy in force, including whether the requesting
      user is the user that submitted the job (job originating user) or
      not (see section 8).  However, the IPP object MUST respond with
      the 'unknown' value for any supported attribute (including all
      REQUIRED attributes) for which the IPP object does not know the
      value, unless it would violate the security policy.  See the
      description of the "out-of-band" values in the beginning of
      Section 4.1.

3.3.5 Hold-Job Operation



   This OPTIONAL operation allows a client to hold a pending job in the
   queue so that it is not eligible for scheduling.  If the Hold-Job
   operation is supported, then the Release-Job operation MUST be
   supported, and vice-versa.  The OPTIONAL "job-hold-until" operation
   attribute allows a client to specify whether to hold the job
   indefinitely or until a specified time period, if supported.

   The IPP object MUST accept or reject the request based on the job's
   current state and transition the job to the indicated new state as
   follows:
















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        Current "job-     New "job-state"   IPP object's response status
            state"                                 code and action:

      'pending'         'pending-held'     'successful-ok'  See Rule 1
      'pending'         'pending'          'successful-ok'  See Rule 2
      'pending-held'    'pending-held'     'successful-ok'  See Rule 1
      'pending-held'    'pending'          'successful-ok'  See Rule 2
      'processing'      'processing'       'client-error-not-possible'
      'processing-      'processing-       'client-error-not-possible'
      stopped'          stopped'
      'completed'       'completed'        'client-error-not-possible'
      'canceled'        'canceled'         'client-error-not-possible'
      'aborted'         'aborted'          'client-error-not-possible'

   Rule 1:  If the implementation supports multiple reasons for a job to
   be in the 'pending-held' state, the IPP object MUST add the 'job-
   hold-until-specified' value to the job's "job-state-reasons"
   attribute.

   Rule 2:  If the IPP object supports the "job-hold-until" operation
   attribute, but the specified time period has already started (or is
   the 'no-hold' value) and there are no other reasons to hold the job,
   the IPP object MUST make the job be a candidate for processing
   immediately (see Section 4.2.2) by putting the job in the 'pending'
   state.

   Note:  In order to keep the Hold-Job operation simple, such a request
   is rejected when the job is in the 'processing' or 'processing-
   stopped' states.  If an operation is needed to hold jobs while in
   these states, it will be added as an additional operation, rather
   than overloading the Hold-Job operation.  Then it is clear to clients
   by querying the Printer object's "operations-supported" (see Section
   4.4.15) and the Job object's "job-state" (see Section 4.3.7)
   attributes which operations are possible.

   Access Rights: The authenticated user (see section 8.3) performing
   this operation must either be the job owner or an operator or
   administrator of the Printer object (see Sections 1 and 8.5).
   Otherwise, the IPP object MUST reject the operation and return:
   'client-error-forbidden', 'client-error-not-authenticated', or
   'client-error-not-authorized' as appropriate.

3.3.5.1 Hold-Job Request



   The groups and operation attributes are the same as for a Cancel-Job
   request (see section 3.3.3.1), with the addition of the following
   Group 1 Operation attribute:




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      "job-hold-until" (type3 keyword | name(MAX)):
         The client OPTIONALLY supplies this Operation attribute.  The
         IPP object MUST support this operation attribute in a Hold-Job
         request, if it supports the "job-hold-until" Job template
         attribute in create operations.  See section 4.2.2.  The IPP
         object SHOULD support the "job-hold-until" Job Template
         attribute for use in job create operations with at least the
         'indefinite' value, if it supports the Hold-Job operation.
         Otherwise, a client cannot create a job and hold it immediately
         (without picking some supported time period in the future).

         If supplied and supported as specified in the Printer's "job-
         hold-until-supported" attribute, the IPP object copies the
         supplied operation attribute to the Job object, replacing the
         job's previous "job-hold-until" attribute, if present, and
         makes the job a candidate for scheduling during the supplied
         named time period.

         If supplied, but either the "job-hold-until" Operation
         attribute itself or the value supplied is not supported, the
         IPP object accepts the request, returns the unsupported
         attribute or value in the Unsupported Attributes Group
         according to section 3.1.7, returns the 'successful-ok-
         ignored-or-substituted-attributes, and holds the job
         indefinitely until a client performs a subsequent Release-Job
         operation.

         If the client (1) supplies a value that specifies a time period
         that has already started or the 'no-hold' value (meaning don't
         hold the job) and (2) the IPP object supports the "job-hold-
         until" operation attribute and there are no other reasons to
         hold the job, the IPP object MUST accept the operation and make
         the job be a candidate for processing immediately (see Section
         4.2.2).

         If the client does not supply a "job-hold-until" Operation
         attribute in the request, the IPP object MUST populate the job
         object with a "job-hold-until" attribute with the 'indefinite'
         value (if IPP object supports the "job-hold-until" attribute)
         and hold the job indefinitely, until a client performs a
         Release-Job operation.

3.3.5.2 Hold-Job Response



   The groups and attributes are the same as for a Cancel-Job response
   (see section 3.3.3.2).





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3.3.6 Release-Job Operation



   This OPTIONAL operation allows a client to release a previously held
   job so that it is again eligible for scheduling.  If the Hold-Job
   operation is supported, then the Release-Job operation MUST be
   supported, and vice-versa.

   This operation removes the "job-hold-until" job attribute, if
   present, from the job object that had been supplied in the create or
   most recent Hold-Job or Restart-Job operation and removes its effect
   on the job.  The IPP object MUST remove the 'job-hold-until-
   specified' value from the job's "job-state-reasons" attribute, if
   present.  See section 4.3.8.

   The IPP object MUST accept or reject the request based on the job's
   current state and transition the job to the indicated new state as
   follows:

        Current "job-   New "job-state"    IPP object's response status
           state"                                code and action:

      'pending'        'pending'        'successful-ok'
                                         No effect on the job.
      'pending-held'   'pending-held'   'successful-ok'  See Rule 1
      'pending-held'   'pending'        'successful-ok'
      'processing'     'processing'     'successful-ok'
                                         No effect on the job.
      'processing-     'processing-     'successful-ok'
       stopped'         stopped'         No effect on the job.
      'completed'      'completed'      'client-error-not-possible'
      'canceled'       'canceled'       'client-error-not-possible'
      'aborted'        'aborted'        'client-error-not-possible'

   Rule 1:  If there are other reasons to keep the job in the 'pending-
   held' state, such as 'resources-are-not-ready', the job remains in
   the 'pending-held' state.  Thus the 'pending-held' state is not just
   for jobs that have the 'job-hold-until' applied to them, but are for
   any reason to keep the job from being a candidate for scheduling and
   processing, such as 'resources-are-not-ready'.  See the "job-hold-
   until" attribute (section 4.2.2).

   Access Rights: The authenticated user (see section 8.3) performing
   this operation must either be the job owner or an operator or
   administrator of the Printer object (see Sections 1 and 8.5).
   Otherwise, the IPP object MUST reject the operation and return:
   'client-error-forbidden', 'client-error-not-authenticated', or
   'client-error-not-authorized' as appropriate.




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   The Release-Job Request and Release-Job Response have the same
   attribute groups and attributes as the Cancel-Job operation (see
   section 3.3.3.1 and 3.3.3.2).

3.3.7 Restart-Job Operation



   This OPTIONAL operation allows a client to restart a job that is
   retained in the queue after processing has completed (see section
   4.3.7.2).

   The job is moved to the 'pending' or 'pending-held' job state and
   restarts at the beginning on the same IPP Printer object with the
   same attribute values.  If any of the documents in the job were
   passed by reference (Print-URI or Send-URI), the Printer MUST re-
   fetch the data, since the semantics of Restart-Job are to repeat all
   Job processing.  The Job Description attributes that accumulate job
   progress, such as "job-impressions-completed", "job-media-sheets-
   completed", and "job-k-octets-processed", MUST be reset to 0 so that
   they give an accurate record of the job from its restart point.  The
   job object MUST continue to use the same "job-uri" and "job-id"
   attribute values.

   Note:  If in the future an operation is needed that does not reset
   the job progress attributes, then a new operation will be defined
   which makes a copy of the job, assigns a new "job-uri" and "job-id"
   to the copy and resets the job progress attributes in the new copy
   only.

   The IPP object MUST accept or reject the request based on the job's
   current state, transition the job to the indicated new state as
   follows:




















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        Current "job-   New "job-state"    IPP object's response status
           state"                                code and action:

      'pending'        'pending'        'client-error-not-possible'
      'pending-held'   'pending-held'   'client-error-not-possible'
      'processing'     'processing'     'client-error-not-possible'
      'processing-     'processing-     'client-error-not-possible'
      stopped'         stopped'
      'completed'      'pending' or     'successful-ok' - job is started
                        'pending-held'   over.
      'completed'      'completed'      'client-error-not-possible' -
                                         see Rule 1
      'canceled'       'pending' or     'successful-ok' - job is started
                        'pending-held'   over.
      'canceled'       'canceled'       'client-error-not-possible' -
                                         see Rule 1
      'aborted'        'pending' or     'successful-ok' - job is started
                        'pending-held'   over.
      'aborted'        'aborted'        'client-error-not-possible' -
                                         see Rule 1

   Rule 1:  If the Job Retention Period has expired for the job in this
   state, then the IPP object rejects the operation.  See section
   4.3.7.2.

   Note:  In order to prevent a user from inadvertently restarting a job
   in the middle, the Restart-Job request is rejected when the job is in
   the 'processing' or 'processing-stopped' states.  If in the future an
   operation is needed to hold or restart jobs while in these states, it
   will be added as an additional operation, rather than overloading the
   Restart-Job operation, so that it is clear that the user intended
   that the current job not be completed.

   Access Rights: The authenticated user (see section 8.3) performing
   this operation must either be the job owner or an operator or
   administrator of the Printer object (see Sections 1 and 8.5).
   Otherwise, the IPP object MUST reject the operation and return:
   'client-error-forbidden', 'client-error-not-authenticated', or
   'client-error-not-authorized' as appropriate.

3.3.7.1 Restart-Job Request



   The groups and attributes are the same as for a Cancel-Job request
   (see section 3.3.3.1), with the addition of the following Group 1
   Operation attribute:






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      "job-hold-until" (type3 keyword | name(MAX)):
         The client OPTIONALLY supplies this attribute.  The IPP object
         MUST support this Operation attribute in a Restart-Job request,
         if it supports the "job-hold-until" Job Template attribute in
         create operations.  See section 4.2.2.  Otherwise, the IPP
         object NEED NOT support the "job-hold-until" Operation
         attribute in a Restart-Job request.

         If supplied and supported as specified in the Printer's "job-
         hold-until-supported" attribute, the IPP object copies the
         supplied Operation attribute to the Job object, replacing the
         job's previous "job-hold-until" attribute, if present, and
         makes the job a candidate for scheduling during the supplied
         named time period.  See section 4.2.2.

         If supplied, but the value is not supported, the IPP object
         accepts the request, returns the unsupported attribute or value
         in the Unsupported Attributes Group according to section 3.1.7,
         returns the 'successful-ok-ignored-or-substituted-attributes'
         status code, and holds the job indefinitely until a client
         performs a subsequent Release-Job operation.

         If supplied, but the "job-hold-until" Operation attribute
         itself is not supported, the IPP object accepts the request,
         returns the unsupported attribute with the out-of-band
         'unsupported' value in the Unsupported Attributes Group
         according to section 3.1.7, returns the 'successful-ok-
         ignored-or-substituted-attributes' status code, and restarts
         the job, i.e., ignores the "job-hold-until" attribute.

         If the client (1) supplies a value that specifies a time period
         that has already started or the 'no-hold' value (meaning don't
         hold the job) and (2) the IPP object supports the "job-hold-
         until" operation attribute and there are no other reasons to
         hold the job, the IPP object makes the job a candidate for
         processing immediately (see Section 4.2.2).

         If the client does not supply a "job-hold-until" operation
         attribute in the request, the IPP object removes the "job-
         hold-until" attribute, if present, from the job.  If there are
         no other reasons to hold the job, the Restart-Job operation
         makes the job a candidate for processing immediately (see
         Section 4.2.2).








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3.3.7.2 Restart-Job Response



   The groups and attributes are the same as for a Cancel-Job response
   (see section 3.3.3.2).

   Note:  In the future an OPTIONAL Modify-Job or Set-Job-Attributes
   operation may be specified that allows the client to modify other
   attributes before releasing the restarted job.

4. Object Attributes



   This section describes the attributes with their corresponding
   attribute syntaxes and values that are part of the IPP model.  The
   sections below show the objects and their associated attributes which
   are included within the scope of this protocol.  Many of these
   attributes are derived from other relevant documents:

      - Document Printing Application (DPA) [ISO10175]
      - RFC 1759 Printer MIB [RFC1759]

   Each attribute is uniquely identified in this document using a
   "keyword" (see section 12.2.1) which is the name of the attribute.
   The keyword is included in the section header describing that
   attribute.

   Note:  Not only are keywords used to identify attributes, but one of
   the attribute syntaxes described below is "keyword" so that some
   attributes have keyword values.  Therefore, these attributes are
   defined as having an attribute syntax that is a set of keywords.

4.1 Attribute Syntaxes



   This section defines the basic attribute syntax types that all
   clients and IPP objects MUST be able to accept in responses and
   accept in requests, respectively.  Each attribute description in
   sections 3 and 4 includes the name of attribute syntax(es) in the
   heading (in parentheses).  A conforming implementation of an
   attribute MUST include the semantics of the attribute syntax(es) so
   identified.  Section 6.3 describes how the protocol can be extended
   with new attribute syntaxes.

   The attribute syntaxes are specified in the following sub-sections,
   where the sub-section heading is the keyword name of the attribute
   syntax inside the single quotes.  In operation requests and responses
   each attribute value MUST be represented as one of the attribute
   syntaxes specified in the sub-section heading for the attribute.  In
   addition, the value of an attribute in a response (but not in a




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   request) MAY be one of the "out-of-band" values whose special
   encoding rules are defined in the "Encoding and Transport" document
   [RFC2910].   Standard "out-of-band" values are:

      'unknown': The attribute is supported by the IPP object, but the
         value is unknown to the IPP object for some reason.
      'unsupported': The attribute is unsupported by the IPP object.
         This value MUST be returned only as the value of an attribute
         in the Unsupported Attributes Group.
      'no-value': The attribute is supported by the Printer object, but
         the administrator has not yet configured a value.

   All attributes in a request MUST have one or more values as defined
   in Sections 4.2 to 4.4.  Thus clients MUST NOT supply attributes with
   "out-of-band" values for operations defined in this document.  All
   attributes in a response MUST have one or more values as defined in
   Sections 4.2 to 4.4 or a single "out-of-band" value.

   Most attributes are defined to have a single attribute syntax.
   However, a few attributes (e.g., "job-sheet", "media", "job-hold-
   until") are defined to have several attribute syntaxes, depending on
   the value.  These multiple attribute syntaxes are separated by the
   "|" character in the sub-section heading to indicate the choice.
   Since each value MUST be tagged as to its attribute syntax in the
   protocol, a single-valued attribute instance may have any one of its
   attribute syntaxes and a multi-valued attribute instance may have a
   mixture of its defined attribute syntaxes.

4.1.1 'text'



   A text attribute is an attribute whose value is a sequence of zero or
   more characters encoded in a maximum of 1023 ('MAX') octets.  MAX is
   the maximum length for each value of any text attribute.  However, if
   an attribute will always contain values whose maximum length is much
   less than MAX, the definition of that attribute will include a
   qualifier that defines the maximum length for values of that
   attribute.  For example:  the "printer-location" attribute is
   specified as "printer-location (text(127))".  In this case, text
   values for "printer-location" MUST NOT exceed 127 octets; if supplied
   with a longer text string via some external interface (other than the
   protocol), implementations are free to truncate to this shorter
   length limitation.

   In this document, all text attributes are defined using the 'text'
   syntax.  However, 'text' is used only for brevity; the formal
   interpretation of 'text' is: 'textWithoutLanguage |
   textWithLanguage'.  That is, for any attribute defined in this
   document using the 'text' attribute syntax, all IPP objects and



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   clients MUST support both the 'textWithoutLanguage' and
   'textWithLanguage' attribute syntaxes.  However, in actual usage and
   protocol execution, objects and clients accept and return only one of
   the two syntax per attribute.  The syntax 'text' never appears "on-
   the-wire".

   Both 'textWithoutLanguage' and 'textWithLanguage' are needed to
   support the real world needs of interoperability between sites and
   systems that use different natural languages as the basis for human
   communication.  Generally, one natural language applies to all text
   attributes in a given request or response. The language is indicated
   by the "attributes-natural-language" operation attribute defined in
   section 3.1.4 or "attributes-natural-language" job attribute defined
   in section 4.3.20, and there is no need to identify the natural
   language for each text string on a value-by-value basis.  In these
   cases, the attribute syntax 'textWithoutLanguage' is used for text
   attributes.  In other cases, the client needs to supply or the
   Printer object needs to return a text value in a natural language
   that is different from the rest of the text values in the request or
   response.  In these cases, the client or Printer object uses the
   attribute syntax 'textWithLanguage' for text attributes (this is the
   Natural Language Override mechanism described in section 3.1.4).

   The 'textWithoutLanguage' and 'textWithLanguage' attribute syntaxes
   are described in more detail in the following sections.

4.1.1.1 'textWithoutLanguage'



   The 'textWithoutLanguage' syntax indicates a value that is sequence
   of zero or more characters encoded in a maximum of 1023 (MAX) octets.
   Text strings are encoded using the rules of some charset.  The
   Printer object MUST support the UTF-8 charset [RFC2279] and MAY
   support additional charsets to represent 'text' values, provided that
   the charsets are registered with IANA [IANA-CS].  See Section 4.1.7
   for the definition of the 'charset' attribute syntax, including
   restricted semantics and examples of charsets.

4.1.1.2 'textWithLanguage'



   The 'textWithLanguage' attribute syntax is a compound attribute
   syntax consisting of two parts: a 'textWithoutLanguage' part encoded
   in a maximum of 1023 (MAX) octets plus an additional
   'naturalLanguage' (see section 4.1.8) part that overrides the natural
   language in force.  The 'naturalLanguage' part explicitly identifies
   the natural language that applies to the text part of that value and
   that value alone.  For any give text attribute, the
   'textWithoutLanguage' part is limited to the maximum length defined
   for that 'text' attribute, and the 'naturalLanguage' part is always



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   limited to 63 (additional) octets.  Using the 'textWithLanguage'
   attribute syntax rather than the normal 'textWithoutLanguage' syntax
   is the so-called Natural Language Override mechanism and MUST be
   supported by all IPP objects and clients.

   If the attribute is multi-valued (1setOf text), then the
   'textWithLanguage' attribute syntax MUST be used to explicitly
   specify each attribute value whose natural language needs to be
   overridden.  Other values in a multi-valued 'text' attribute in a
   request or a response revert to the natural language of the operation
   attribute.

   In a create request, the Printer object MUST accept and store with
   the Job object any natural language in the "attributes-natural-
   language" operation attribute, whether the Printer object supports
   that natural language or not.  Furthermore, the Printer object MUST
   accept and store any 'textWithLanguage' attribute value, whether the
   Printer object supports that natural language or not.  These
   requirements are independent of the value of the "ipp-attribute-
   fidelity" operation attribute that the client MAY supply.

   Example:  If the client supplies the "attributes-natural-language"
   operation attribute with the value: 'en' indicating English, but the
   value of the "job-name" attribute is in French, the client MUST use
   the 'textWithLanguage' attribute syntax with the following two
   values:

      'fr': Natural Language Override indicating French
      'Rapport Mensuel': the job name in French

   See the "Encoding and Transport" document [RFC2910] section 3.9 for
   the encoding of the two parts and Appendix A for a detailed example
   of the 'textWithLanguage' attribute syntax.

4.1.2 'name'



   This syntax type is used for user-friendly strings, such as a Printer
   name, that, for humans, are more meaningful than identifiers.  Names
   are never translated from one natural language to another.  The
   'name' attribute syntax is essentially the same as 'text', including
   the REQUIRED support of UTF-8 except that the sequence of characters
   is limited so that its encoded form MUST NOT exceed 255 (MAX) octets.

   Also like 'text', 'name' is really an abbreviated notation for either
   'nameWithoutLanguage' or 'nameWithLanguage'.  That is, all IPP
   objects and clients MUST support both the 'nameWithoutLanguage' and
   'nameWithLanguage' attribute syntaxes.  However, in actual usage and




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   protocol execution, objects and clients accept and return only one of
   the two syntax per attribute.  The syntax 'name' never appears "on-
   the-wire".

   Only the 'text' and 'name' attribute syntaxes permit the Natural
   Language Override mechanism.

   Some attributes are defined as 'type3 keyword | name'.  These
   attributes support values that are either type3 keywords or names.
   This dual-syntax mechanism enables a site administrator to extend
   these attributes to legally include values that are locally defined
   by the site administrator.  Such names are not registered with IANA.

4.1.2.1 'nameWithoutLanguage'



   The 'nameWithoutLanguage' syntax indicates a value that is sequence
   of zero or more characters encoded in a maximum of 255 (MAX) octets.

4.1.2.2 'nameWithLanguage'



   The 'nameWithLanguage' attribute syntax is a compound attribute
   syntax consisting of two parts: a 'nameWithoutLanguage' part encoded
   in a maximum of 1023 (MAX) octets plus an additional
   'naturalLanguage' (see section 4.1.8) part that overrides the natural
   language in force.  The 'naturalLanguage' part explicitly identifies
   the natural language that applies to that name value and that name
   value alone.  For any give text attribute, the 'textWithoutLanguage'
   part is limited to the maximum length defined for that 'text'
   attribute, and the 'naturalLanguage' part is always limited to 63
   (additional) octets.  Using the 'textWithLanguage' attribute syntax
   rather than the normal 'textWithoutLanguage' syntax is the so-called
   Natural Language Override mechanism and MUST be supported by all IPP
   objects and clients.

   The 'nameWithLanguage' attribute syntax behaves the same as the
   'textWithLanguage' syntax.  Using the 'textWithLanguage' attribute
   syntax rather than the normal 'textWithoutLanguage' syntax is the
   so-called Natural Language Override mechanism and MUST be supported
   by all IPP objects and clients.  If a name is in a language that is
   different than the rest of the object or operation, then this
   'nameWithLanguage' syntax is used rather than the generic
   'nameWithoutLanguage' syntax.

   If the attribute is multi-valued (1setOf text), then the
   'nameWithLanguage' attribute syntax MUST be used to explicitly
   specify each attribute value whose natural language needs to be
   overridden.




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   Other values in a multi-valued 'name' attribute in a request or a
   response revert to the natural language of the operation attribute.

   In a create request, the Printer object MUST accept and store with
   the Job object any natural language in the "attributes-natural-
   language" operation attribute, whether the Printer object supports
   that natural language or not.  Furthermore, the Printer object MUST
   accept and store any 'nameWithLanguage' attribute value, whether the
   Printer object supports that natural language or not.  These
   requirements are independent of the value of the "ipp-attribute-
   fidelity" operation attribute that the client MAY supply.

   Example:  If the client supplies the "attributes-natural-language"
   operation attribute with the value:  'en' indicating English, but the
   "printer-name" attribute is in German, the client MUST use the
   'nameWithLanguage' attribute syntax as follows:

      'de':  Natural Language Override indicating German
      'Farbdrucker':  the Printer name in German

   See the "Encoding and Transport" document [RFC2910] section 3.9 for
   the encoding of the two parts and Appendix A for a detailed example
   of the 'nameWithLanguage' attribute syntax.

4.1.2.3 Matching 'name' attribute values



   For purposes of matching two 'name' attribute values for equality,
   such as in job validation (where a client-supplied value for
   attribute "xxx" is checked to see if the value is among the values of
   the Printer object's corresponding "xxx-supported" attribute), the
   following match rules apply:

      1. 'keyword' values never match 'name' values.

      2. 'name' (nameWithoutLanguage and nameWithLanguage) values match
         if (1) the name parts match and (2) the Associated Natural-
         Language parts (see section 3.1.4.1) match.  The matching rules
         are:

         a. the name parts match if the two names are identical
            character by character, except it is RECOMMENDED that case
            be ignored.  For example: 'Ajax-letter-head-white' MUST
            match 'Ajax-letter-head-white' and SHOULD match 'ajax-
            letter-head-white' and 'AJAX-LETTER-HEAD-WHITE'.







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         b. the Associated Natural-Language parts match if the shorter
            of the two meets the syntactic requirements of RFC 1766
            [RFC1766] and matches byte for byte with the longer.  For
            example, 'en' matches 'en', 'en-us' and 'en-gb', but matches
            neither 'fr' nor 'e'.

4.1.3 'keyword'



   The 'keyword' attribute syntax is a sequence of characters, length: 1
   to 255, containing only the US-ASCII [ASCII] encoded values for
   lowercase letters ("a" - "z"), digits ("0" - "9"), hyphen ("-"), dot
   ("."), and underscore ("_").  The first character MUST be a lowercase
   letter.  Furthermore, keywords MUST be in U.S. English.

   This syntax type is used for enumerating semantic identifiers of
   entities in the abstract protocol, i.e., entities identified in this
   document.  Keywords are used as attribute names or values of
   attributes.  Unlike 'text' and 'name' attribute values, 'keyword'
   values MUST NOT use the Natural Language Override mechanism, since
   they MUST always be US-ASCII and U.S. English.

   Keywords are for use in the protocol.  A user interface will likely
   provide a mapping between protocol keywords and displayable user-
   friendly words and phrases which are localized to the natural
   language of the user.  While the keywords specified in this document
   MAY be displayed to users whose natural language is U.S. English,
   they MAY be mapped to other U.S. English words for U.S. English
   users, since the user interface is outside the scope of this
   document.

   In the definition for each attribute of this syntax type, the full
   set of defined keyword values for that attribute are listed.

   When a keyword is used to represent an attribute (its name), it MUST
   be unique within the full scope of all IPP objects and attributes.
   When a keyword is used to represent a value of an attribute, it MUST
   be unique just within the scope of that attribute.  That is, the same
   keyword MUST NOT be used for two different values within the same
   attribute to mean two different semantic ideas.  However, the same
   keyword MAY be used across two or more attributes, representing
   different semantic ideas for each attribute.  Section 6.1 describes
   how the protocol can be extended with new keyword values.  Examples
   of attribute name keywords:

      "job-name"
      "attributes-charset"





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   Note:  This document uses "type1", "type2", and "type3" prefixes to
   the "keyword" basic syntax to indicate different levels of review for
   extensions (see section 6.1).

4.1.4 'enum'



   The 'enum' attribute syntax is an enumerated integer value that is in
   the range from 1 to 2**31 - 1 (MAX).   Each value has an associated
   'keyword' name.  In the definition for each attribute of this syntax
   type, the full set of possible values for that attribute are listed.
   This syntax type is used for attributes for which there are enum
   values assigned by other standards, such as SNMP MIBs.  A number of
   attribute enum values in this document are also used for
   corresponding attributes in other standards [RFC1759].  This syntax
   type is not used for attributes to which the administrator may assign
   values.  Section 6.1 describes how the protocol can be extended with
   new enum values.

   Enum values are for use in the protocol.  A user interface will
   provide a mapping between protocol enum values and displayable user-
   friendly words and phrases which are localized to the natural
   language of the user.  While the enum symbols specified in this
   document MAY be displayed to users whose natural language is U.S.
   English, they MAY be mapped to other U.S. English words for U.S.
   English users, since the user interface is outside the scope of this
   document.

   Note: SNMP MIBs use '2' for 'unknown' which corresponds to the IPP
   "out-of-band" value 'unknown'.  See the description of the "out-of-
   band" values at the beginning of Section 4.1.  Therefore, attributes
   of type 'enum' start at '3'.

   Note:  This document uses "type1", "type2", and "type3" prefixes to
   the "enum" basic syntax to indicate different levels of review for
   extensions (see section 6.1).

4.1.5 'uri'



   The 'uri' attribute syntax is any valid Uniform Resource Identifier
   or URI [RFC2396].  Most often, URIs are simply Uniform Resource
   Locators or URLs.  The maximum length of URIs used as values of IPP
   attributes is 1023 octets.  Although most other IPP attribute syntax
   types allow for only lower-cased values, this attribute syntax type
   conforms to the case-sensitive and case-insensitive rules specified
   in [RFC2396].  See also [IPP-IIG] for a discussion of case in URIs.






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4.1.6 'uriScheme'



   The 'uriScheme' attribute syntax is a sequence of characters
   representing a URI scheme according to RFC 2396 [RFC2396].  Though
   RFC 2396 requires that the values be case-insensitive, IPP requires
   all lower case values in IPP attributes to simplify comparing by IPP
   clients and Printer objects.

   Standard values for this syntax type are the following keywords:

      'ipp':  for IPP schemed URIs (e.g., "ipp:...")
      'http':  for HTTP schemed URIs (e.g., "http:...")
      'https':  for use with HTTPS schemed URIs (e.g., "https:...") (not
         on IETF standards track)
      'ftp': for FTP schemed URIs (e.g., "ftp:...")
      'mailto': for SMTP schemed URIs (e.g., "mailto:...")
      'file': for file schemed URIs (e.g., "file:...")

   A Printer object MAY support any URI 'scheme' that has been
   registered with IANA [IANA-MT]. The maximum length of URI 'scheme'
   values used to represent IPP attribute values is 63 octets.

4.1.7 'charset'



   The 'charset' attribute syntax is a standard identifier for a
   charset.  A charset is a coded character set and encoding scheme.
   Charsets are used for labeling certain document contents and 'text'
   and 'name' attribute values.  The syntax and semantics of this
   attribute syntax are specified in RFC 2046 [RFC2046] and contained in
   the IANA character-set Registry [IANA-CS] according to the IANA
   procedures [RFC2278].  Though RFC 2046 requires that the values be
   case-insensitive US-ASCII [ASCII], IPP requires all lower case values
   in IPP attributes to simplify comparing by IPP clients and Printer
   objects.  When a character-set in the IANA registry has more than one
   name (alias), the name labeled as "(preferred MIME name)", if
   present, MUST be used.

   The maximum length of 'charset' values used to represent IPP
   attribute values is 63 octets.

   Some examples are:

      'utf-8':  ISO 10646 Universal Multiple-Octet Coded Character Set
         (UCS) represented as the UTF-8 [RFC2279] transfer encoding
         scheme in which US-ASCII is a subset charset.
      'us-ascii':  7-bit American Standard Code for Information
         Interchange (ASCII), ANSI X3.4-1986 [ASCII].  That standard




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         defines US-ASCII, but RFC 2045 [RFC2045] eliminates most of the
         control characters from conformant usage in MIME and IPP.
      'iso-8859-1':  8-bit One-Byte Coded Character Set, Latin Alphabet
         Nr 1 [ISO8859-1].  That standard defines a coded character set
         that is used by Latin languages in the Western Hemisphere and
         Western Europe.  US-ASCII is a subset charset.

   Some attribute descriptions MAY place additional requirements on
   charset values that may be used, such as REQUIRED values that MUST be
   supported or additional restrictions, such as requiring that the
   charset have US- ASCII as a subset charset.

4.1.8 'naturalLanguage'



   The 'naturalLanguage' attribute syntax is a standard identifier for a
   natural language and optionally a country.  The values for this
   syntax type are defined by RFC 1766 [RFC1766].  Though RFC 1766
   requires that the values be case-insensitive US-ASCII [ASCII], IPP
   requires all lower case to simplify comparing by IPP clients and
   Printer objects.  Examples include:

      'en':  for English
      'en-us': for US English
      'fr': for French
      'de':  for German

   The maximum length of 'naturalLanguage' values used to represent IPP
   attribute values is 63 octets.

4.1.9 'mimeMediaType'



   The 'mimeMediaType' attribute syntax is the Internet Media Type
   (sometimes called MIME type) as defined by RFC 2046 [RFC2046] and
   registered according to the procedures of RFC 2048 [RFC2048] for
   identifying a document format.  The value MAY include a charset, or
   other, parameter, depending on the specification of the Media Type in
   the IANA Registry [IANA-MT].  Although most other IPP syntax types
   allow for only lower-cased values, this syntax type allows for
   mixed-case values which are case-insensitive.

   Examples are:
      'text/html': An HTML document
      'text/plain': A plain text document in US-ASCII (RFC 2046
         indicates that in the absence of the charset parameter MUST
         mean US-ASCII rather than simply unspecified) [RFC2046].
      'text/plain; charset=US-ASCII':  A plain text document in US-ASCII
         [52, 56].




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      'text/plain; charset=ISO-8859-1':  A plain text document in ISO
         8859-1 (Latin 1) [ISO8859-1].
      'text/plain; charset=utf-8':  A plain text document in ISO 10646
         represented as UTF-8 [RFC2279]
      'application/postscript':  A PostScript document [RFC2046]
      'application/vnd.hp-PCL':  A PCL document [IANA-MT] (charset
         escape sequence embedded in the document data)
      'application/pdf':  Portable Document Format - see IANA MIME Media
         Type registry
      'application/octet-stream': Auto-sense - see section 4.1.9.1

   The maximum length of a 'mimeMediaType' value to represent IPP
   attribute values is 255 octets.

4.1.9.1 Application/octet-stream -- Auto-Sensing the document format



   One special type is 'application/octet-stream'.  If the Printer
   object supports this value, the Printer object MUST be capable of
   auto-sensing the format of the document data using an
   implementation-dependent method that examines some number of octets
   of the document data, either as part of the create operation and/or
   at document processing time.  During auto-sensing, a Printer may
   determine that the document-data has a format that the Printer
   doesn't recognize.  If the Printer determines this problem before
   returning an operation response, it rejects the request and returns
   the 'client-error-document-format-not-supported' status code.  If the
   Printer determines this problem after accepting the request and
   returning an operation response with one of the successful status
   codes, the Printer adds the 'unsupported-document-format' value to
   the job's "job-state-reasons" attribute.

   If the Printer object's default value attribute "document-format-
   default" is set to 'application/octet-stream', the Printer object not
   only supports auto-sensing of the document format, but will depend on
   the result of applying its auto-sensing when the client does not
   supply the "document-format" attribute.  If the client supplies a
   document format value, the Printer MUST rely on the supplied
   attribute, rather than trust its auto-sensing algorithm.  To
   summarize:

      1. If the client does not supply a document format value, the
         Printer MUST rely on its default value setting (which may be
         'application/octet-stream' indicating an auto-sensing
         mechanism).
      2. If the client supplies a value other than 'application/octet-
         stream', the client is supplying valid information about the
         format of the document data and the Printer object MUST trust
         the client supplied value more than the outcome of applying an



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         automatic format detection mechanism.  For example, the client
         may be requesting the printing of a PostScript file as a
         'text/plain' document.  The Printer object MUST print a text
         representation of the PostScript commands rather than interpret
         the stream of PostScript commands and print the result.
      3. If the client supplies a value of 'application/octet-stream',
         the client is indicating that the Printer object MUST use its
         auto-sensing mechanism on the client supplied document data
         whether auto-sensing is the Printer object's default or not.

   Note:  Since the auto-sensing algorithm is probabilistic, if the
   client requests both auto-sensing ("document-format" set to
   'application/octet-stream') and true fidelity ("ipp-attribute-
   fidelity" set to 'true'), the Printer object might not be able to
   guarantee exactly what the end user intended (the auto-sensing
   algorithm might mistake one document format for another), but it is
   able to guarantee that its auto-sensing mechanism be used.

   When a Printer performs auto-sensing of a document in a submitted
   job, it is RECOMMENDED that the Printer indicate to the user that
   such auto-sensing has occurred and which document-format was auto-
   sensed by printing that information on the job's job-start-sheet.

4.1.10 'octetString'



   The 'octetString' attribute syntax is a sequence of octets encoded in
   a maximum of 1023 octets which is indicated in sub-section headers
   using the notation: octetString(MAX).  This syntax type is used for
   opaque data.

4.1.11 'boolean'



   The 'boolean' attribute syntax has only two values:  'true' and
   'false'.

4.1.12 'integer'



   The 'integer' attribute syntax is an integer value that is in the
   range from -2**31 (MIN) to 2**31 - 1 (MAX).  Each individual
   attribute may specify the range constraint explicitly in sub-section
   headers if the range is different from the full range of possible
   integer values.  For example:  job-priority (integer(1:100)) for the
   "job-priority" attribute.  However, the enforcement of that
   additional constraint is up to the IPP objects, not the protocol.







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4.1.13 'rangeOfInteger'



   The 'rangeOfInteger' attribute syntax is an ordered pair of integers
   that defines an inclusive range of integer values.  The first integer
   specifies the lower bound and the second specifies the upper bound.
   If a range constraint is specified in the header description for an
   attribute in this document whose attribute syntax is 'rangeOfInteger'
   (i.e., 'X:Y' indicating X as a minimum value and Y as a maximum
   value), then the constraint applies to both integers.

4.1.14 'dateTime'



   The 'dateTime' attribute syntax is a standard, fixed length, 11 octet
   representation of the "DateAndTime" syntax as defined in RFC 2579
   [RFC2579].  RFC 2579 also identifies an 8 octet representation of a
   "DateAndTime" value, but IPP objects MUST use the 11 octet
   representation.  A user interface will provide a mapping between
   protocol dateTime values and displayable user-friendly words or
   presentation values and phrases which are localized to the natural
   language and date format of the user, including time zone.

4.1.15 'resolution'



   The 'resolution' attribute syntax specifies a two-dimensional
   resolution in the indicated units.  It consists of 3 values: a cross
   feed direction resolution (positive integer value), a feed direction
   resolution (positive integer value), and a units value.  The
   semantics of these three components are taken from the Printer MIB
   [RFC1759] suggested values.  That is, the cross feed direction
   component resolution component is the same as the
   prtMarkerAddressabilityXFeedDir object in the Printer MIB, the feed
   direction component resolution component is the same as the
   prtMarkerAddressabilityFeedDir in the Printer MIB, and the units
   component is the same as the prtMarkerAddressabilityUnit object in
   the Printer MIB (namely, '3' indicates dots per inch and '4'
   indicates dots per centimeter).  All three values MUST be present
   even if the first two values are the same.  Example:  '300', '600',
   '3' indicates a 300 dpi cross-feed direction resolution, a 600 dpi
   feed direction resolution, since a '3' indicates dots per inch (dpi).

4.1.16 '1setOf  X'



   The '1setOf  X' attribute syntax is 1 or more values of attribute
   syntax type X.  This syntax type is used for multi-valued attributes.
   The syntax type is called '1setOf' rather than just 'setOf' as a
   reminder that the set of values MUST NOT be empty (i.e., a set of





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   size 0).  Sets are normally unordered.  However each attribute
   description of this type may specify that the values MUST be in a
   certain order for that attribute.

4.2 Job Template Attributes



   Job Template attributes describe job processing behavior.  Support
   for Job Template attributes by a Printer object is OPTIONAL (see
   section 12.2.3 for a description of support for OPTIONAL attributes).
   Also, clients OPTIONALLY supply Job Template attributes in create
   requests.

   Job Template attributes conform to the following rules.  For each Job
   Template attribute called "xxx":

      1. If the Printer object supports "xxx" then it MUST support both
         a "xxx-default" attribute (unless there is a "No" in the table
         below) and a "xxx-supported" attribute.  If the Printer object
         doesn't support "xxx", then it MUST support neither an "xxx-
         default" attribute nor an "xxx-supported" attribute, and it
         MUST treat an attribute "xxx" supplied by a client as
         unsupported.  An attribute "xxx" may be supported for some
         document formats and not supported for other document formats.
         For example, it is expected that a Printer object would only
         support "orientation-requested" for some document formats (such
         as 'text/plain' or 'text/html') but not others (such as
         'application/postscript').

      2. "xxx" is OPTIONALLY supplied by the client in a create request.
         If "xxx" is supplied, the client is indicating a desired job
         processing behavior for this Job.  When "xxx" is not supplied,
         the client is indicating that the Printer object apply its
         default job processing behavior at job processing time if the
         document content does not contain an embedded instruction
         indicating an xxx-related behavior.

         Since an administrator MAY change the default value attribute
         after a Job object has been submitted but before it has been
         processed, the default value used by the Printer object at job
         processing time may be different that the default value in
         effect at job submission time.

      3. The "xxx-supported" attribute is a Printer object attribute
         that describes which job processing behaviors are supported by
         that Printer object.  A client can query the Printer object to
         find out what xxx-related behaviors are supported by inspecting
         the returned values of the "xxx-supported" attribute.




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         Note: The "xxx" in each "xxx-supported" attribute name is
         singular, even though an "xxx-supported" attribute usually has
         more than one value, such as "job-sheet-supported", unless the
         "xxx" Job Template attribute is plural, such as "finishings" or
         "sides".  In such cases the "xxx-supported" attribute names
         are: "finishings- supported" and "sides-supported".

      4. The "xxx-default" default value attribute describes what will
         be done at job processing time when no other job processing
         information is supplied by the client (either explicitly as an
         IPP attribute in the create request or implicitly as an
         embedded instruction within the document data).

   If an application wishes to present an end user with a list of
   supported values from which to choose, the application SHOULD query
   the Printer object for its supported value attributes.  The
   application SHOULD also query the default value attributes.  If the
   application then limits selectable values to only those value that
   are supported, the application can guarantee that the values supplied
   by the client in the create request all fall within the set of
   supported values at the Printer.  When querying the Printer, the
   client MAY enumerate each attribute by name in the Get-Printer-
   Attributes Request, or the client MAY just name the "job-template"
   group in order to get the complete set of supported attributes (both
   supported and default attributes).

   The "finishings" attribute is an example of a Job Template attribute.
   It can take on a set of values such as 'staple', 'punch', and/or
   'cover'.  A client can query the Printer object for the "finishings-
   supported" attribute and the "finishings-default" attribute.  The
   supported attribute contains a set of supported values.  The default
   value attribute contains the finishing value(s) that will be used for
   a new Job if the client does not supply a "finishings" attribute in
   the create request and the document data does not contain any
   corresponding finishing instructions.  If the client does supply the
   "finishings" attribute in the create request, the IPP object
   validates the value or values to make sure that they are a subset of
   the supported values identified in the Printer object's "finishings-
   supported" attribute.  See section 3.1.7.

   The table below summarizes the names and relationships for all Job
   Template attributes. The first column of the table (labeled "Job
   Attribute") shows the name and syntax for each Job Template attribute
   in the Job object. These are the attributes that can optionally be
   supplied by the client in a create request.   The last two columns
   (labeled "Printer: Default Value Attribute" and "Printer: Supported
   Values Attribute") show the name and syntax for each Job Template
   attribute in the Printer object (the default value attribute and the



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   supported values attribute).  A "No" in the table means the Printer
   MUST NOT support the attribute (that is, the attribute is simply not
   applicable).  For brevity in the table, the 'text' and 'name' entries
   do not show the maximum length for each attribute.

     +===================+======================+======================+
     | Job Attribute     |Printer: Default Value|  Printer: Supported  |
     |                   |   Attribute          |   Values Attribute   |
     +===================+======================+======================+
     | job-priority      | job-priority-default |job-priority-supported|
     | (integer 1:100)   | (integer 1:100)      |(integer 1:100)       |
     +-------------------+----------------------+----------------------+
     | job-hold-until    | job-hold-until-      |job-hold-until-       |
     | (type3 keyword |  |  default             | supported            |
     |    name)          |  (type3 keyword |    |(1setOf (             |
     |                   |    name)             |type3 keyword | name))|
     +-------------------+----------------------+----------------------+
     | job-sheets        | job-sheets-default   |job-sheets-supported  |
     | (type3 keyword |  | (type3 keyword |     |(1setOf (             |
     |    name)          |    name)             |type3 keyword | name))|
     +-------------------+----------------------+----------------------+
     |multiple-document- |multiple-document-    |multiple-document-    |
     | handling          | handling-default     |handling-supported    |
     | (type2 keyword)   | (type2 keyword)      |(1setOf type2 keyword)|
     +-------------------+----------------------+----------------------+
     | copies            | copies-default       | copies-supported     |
     | (integer (1:MAX)) | (integer (1:MAX))    | (rangeOfInteger      |
     |                   |                      |       (1:MAX))       |
     +-------------------+----------------------+----------------------+
     | finishings        | finishings-default   | finishings-supported |
     |(1setOf type2 enum)|(1setOf type2 enum)   |(1setOf type2 enum)   |
     +-------------------+----------------------+----------------------+
     | page-ranges       | No                   | page-ranges-         |
     | (1setOf           |                      | supported (boolean)  |
     |   rangeOfInteger  |                      |                      |
     |        (1:MAX))   |                      |                      |
     +-------------------+----------------------+----------------------+
     | sides             | sides-default        | sides-supported      |
     | (type2 keyword)   | (type2 keyword)      |(1setOf type2 keyword)|
     +-------------------+----------------------+----------------------+
     | number-up         | number-up-default    | number-up-supported  |
     | (integer (1:MAX)) | (integer (1:MAX))    |(1setOf (integer      |
     |                   |                      | (1:MAX) |            |
     |                   |                      |  rangeOfInteger      |
     |                   |                      |   (1:MAX)))          |






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     +-------------------+----------------------+----------------------+
     | orientation-      |orientation-requested-|orientation-requested-|
     |  requested        |  default             |  supported           |
     |   (type2 enum)    |  (type2 enum)        |  (1setOf type2 enum) |
     +-------------------+----------------------+----------------------+
     | media             | media-default        | media-supported      |
     | (type3 keyword |  | (type3 keyword |     |(1setOf (             |
     |    name)          |    name)             |type3 keyword | name))|
     |                   |                      |                      |
     |                   |                      | media-ready          |
     |                   |                      |(1setOf (             |
     |                   |                      |type3 keyword | name))|
     +-------------------+----------------------+----------------------+
     | printer-resolution| printer-resolution-  | printer-resolution-  |
     | (resolution)      |  default             | supported            |
     |                   | (resolution)         |(1setOf resolution)   |
     +-------------------+----------------------+----------------------+
     | print-quality     | print-quality-default| print-quality-       |
     | (type2 enum)      | (type2 enum)         | supported            |
     |                   |                      |(1setOf type2 enum)   |
     +-------------------+----------------------+----------------------+

4.2.1 job-priority (integer(1:100))



   This attribute specifies a priority for scheduling the Job. A higher
   value specifies a higher priority. The value 1 indicates the lowest
   possible priority. The value 100 indicates the highest possible
   priority.  Among those jobs that are ready to print, a Printer MUST
   print all jobs with a priority value of n before printing those with
   a priority value of n-1 for all n.

   If the Printer object supports this attribute, it MUST always support
   the full range from 1 to 100.  No administrative restrictions are
   permitted.  This way an end-user can always make full use of the
   entire range with any Printer object.  If privileged jobs are
   implemented outside IPP/1.1, they MUST have priorities higher than
   100, rather than restricting the range available to end-users.

   If the client does not supply this attribute and this attribute is
   supported by the Printer object, the Printer object MUST use the
   value of the Printer object's "job-priority-default" at job
   submission time (unlike most Job Template attributes that are used if
   necessary at job processing time).

   The syntax for the "job-priority-supported" is also integer(1:100).
   This single integer value indicates the number of priority levels
   supported.  The Printer object MUST take the value supplied by the
   client and map it to the closest integer in a sequence of n integers



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   values that are evenly distributed over the range from 1 to 100 using
   the formula:

      roundToNearestInt((100x+50)/n)

   where n is the value of "job-priority-supported" and x ranges from 0
   through n-1.

   For example, if n=1 the sequence of values is 50;  if n=2, the
   sequence of values is:  25 and 75;  if n = 3, the sequence of values
   is:  17, 50 and 83;  if n = 10, the sequence of values is: 5, 15, 25,
   35, 45, 55, 65, 75, 85, and 95;  if n = 100, the sequence of values
   is:  1, 2, 3, ... 100.

   If the value of the Printer object's "job-priority-supported" is 10
   and the client supplies values in the range 1 to 10, the Printer
   object maps them to 5, in the range 11 to 20, the Printer object maps
   them to 15, etc.

4.2.2 job-hold-until (type3 keyword | name (MAX))



   This attribute specifies the named time period during which the Job
   MUST become a candidate for printing.

   Standard keyword values for named time periods are:

      'no-hold': immediately, if there are not other reasons to hold the
         job
      'indefinite':  - the job is held indefinitely, until a client
         performs a Release-Job (section 3.3.6)
      'day-time': during the day
      'evening': evening
      'night': night
      'weekend': weekend
      'second-shift': second-shift (after close of business)
      'third-shift': third-shift (after midnight)

   An administrator MUST associate allowable print times with a named
   time period (by means outside the scope of this IPP/1.1 document).
   An administrator is encouraged to pick names that suggest the type of
   time period. An administrator MAY define additional values using the
   'name' or 'keyword' attribute syntax, depending on implementation.

   If the value of this attribute specifies a time period that is in the
   future, the Printer SHOULD add the 'job-hold-until-specified' value
   to the job's "job-state-reasons" attribute, MUST move the job to the





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   'pending-held' state, and MUST NOT schedule the job for printing
   until the specified time-period arrives.

   When the specified time period arrives, the Printer MUST remove the
   'job-hold-until-specified' value from the job's "job-state-reason"
   attribute, if present.  If there are no other job state reasons that
   keep the job in the 'pending-held' state, the Printer MUST consider
   the job as a candidate for processing by moving the job to the
   'pending' state.

   If this job attribute value is the named value 'no-hold', or the
   specified time period has already started, the job MUST be a
   candidate for processing immediately.

   If the client does not supply this attribute and this attribute is
   supported by the Printer object, the Printer object MUST use the
   value of the Printer object's "job-hold-until-default" at job
   submission time (unlike most Job Template attributes that are used if
   necessary at job processing time).

4.2.3 job-sheets (type3 keyword | name(MAX))



   This attribute determines which job start/end sheet(s), if any, MUST
   be printed with a job.

   Standard keyword values are:

      'none': no job sheet is printed
      'standard': one or more site specific standard job sheets are
         printed, e.g. a single start sheet or both start and end sheet is
         printed

   An administrator MAY define additional values using the 'name' or
   'keyword' attribute syntax, depending on implementation.

   The effect of this attribute on jobs with multiple documents MAY be
   affected by the "multiple-document-handling" job attribute (section
   4.2.4), depending on the job sheet semantics.

4.2.4 multiple-document-handling (type2 keyword)



   This attribute is relevant only if a job consists of two or more
   documents. This attribute MUST be supported with at least one value
   if the Printer supports multiple documents per job (see sections
   3.2.4 and 3.3.1).  The attribute controls finishing operations and
   the placement of one or more print-stream pages into impressions and
   onto media sheets.  When the value of the "copies" attribute exceeds
   1, it also controls the order in which the copies that result from



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   processing the documents are produced. For the purposes of this
   explanations, if "a" represents an instance of document data, then
   the result of processing the data in document "a" is a sequence of
   media sheets represented by "a(*)".

   Standard keyword values are:

      'single-document': If a Job object has multiple documents, say,
         the document data is called a and b, then the result of
         processing all the document data (a and then b) MUST be treated
         as a single sequence of media sheets for finishing operations;
         that is, finishing would be performed on the concatenation of
         the sequences a(*),b(*).  The Printer object MUST NOT force the
         data in each document instance to be formatted onto a new
         print-stream page, nor to start a new impression on a new media
         sheet. If more than one copy is made, the ordering of the sets
         of media sheets resulting from processing the document data
         MUST be a(*), b(*), a(*), b(*), start on a new media sheet.
      'separate-documents-uncollated-copies': If a Job object has
         multiple documents, say, the document data is called a and b,
         then the result of processing the data in each document
         instance MUST be treated as a single sequence of media sheets
         for finishing operations; that is, the sets a(*) and b(*) would
         each be finished separately. The Printer object MUST force each
         copy of the result of processing the data in a single document
         to start on a new media sheet. If more than one copy is made,
         the ordering of the sets of media sheets resulting from
         processing the document data MUST be a(*), a(*), ..., b(*),
         b(*) ... .
      'separate-documents-collated-copies': If a Job object has multiple
         documents, say, the document data is called a and b, then the
         result of processing the data in each document instance MUST be
         treated as a single sequence of media sheets for finishing
         operations; that is, the sets a(*) and b(*) would each be
         finished separately. The Printer object MUST force each copy of
         the result of processing the data in a single document to start
         on a new media sheet.  If more than one copy is made, the
         ordering of the sets of media sheets resulting from processing
         the document data MUST be a(*), b(*), a(*), b(*), ... .
      'single-document-new-sheet':  Same as 'single-document', except
         that the Printer object MUST ensure that the first impression
         of each document instance in the job is placed on a new media
         sheet.  This value allows multiple documents to be stapled
         together with a single staple where each document starts on a
         new sheet.






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   The 'single-document' value is the same as 'separate-documents-
   collated-copies' with respect to ordering of print-stream pages, but
   not media sheet generation, since 'single-document' will put the
   first page of the next document on the back side of a sheet if an odd
   number of pages have been produced so far for the job, while
   'separate-documents-collated- copies' always forces the next document
   or document copy on to a new sheet.  In addition, if the "finishings"
   attribute specifies 'staple', then with 'single-document', documents
   a and b are stapled together as a single document with no regard to
   new sheets, with 'single-document-new-sheet', documents a and b are
   stapled together as a single document, but document b starts on a new
   sheet, but with 'separate-documents-uncollated-copies' and
   'separate-documents-collated-copies', documents a and b are stapled
   separately.

   Note: None of these values provide means to produce uncollated sheets
   within a document, i.e., where multiple copies of sheet n are
   produced before sheet n+1 of the same document.

   The relationship of this attribute and the other attributes that
   control document processing is described in section 15.3.

4.2.5 copies (integer(1:MAX))



   This attribute specifies the number of copies to be printed.

   On many devices the supported number of collated copies will be
   limited by the number of physical output bins on the device, and may
   be different from the number of uncollated copies which can be
   supported.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.6 finishings (1setOf type2 enum)



   This attribute identifies the finishing operations that the Printer
   uses for each copy of each printed document in the Job. For Jobs with
   multiple documents, the "multiple-document-handling" attribute
   determines what constitutes a "copy" for purposes of finishing.








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   Standard enum values are:

   Value  Symbolic Name and Description

   '3'    'none':  Perform no finishing
   '4'    'staple':  Bind the document(s) with one or more staples. The
             exact number and placement of the staples is site-
             defined.
   '5'    'punch':  This value indicates that holes are required in the
             finished document. The exact number and placement of the
             holes is site-defined  The punch specification MAY be
             satisfied (in a site- and implementation-specific manner)
             either by drilling/punching, or by substituting pre-
             drilled media.
   '6'    'cover':  This value is specified when it is desired to select
             a non-printed (or pre-printed) cover for the document.
             This does not supplant the specification of a printed
             cover (on cover stock medium) by the document itself.
   '7'    'bind':  This value indicates that a binding is to be applied
             to the document; the type and placement of the binding is
             site-defined.
   '8'    'saddle-stitch':  Bind the document(s) with one or more
             staples (wire stitches) along the middle fold.  The exact
             number and placement of the staples and the middle fold
             is implementation and/or site-defined.
   '9'    'edge-stitch':  Bind the document(s) with one or more staples
             (wire stitches) along one edge.  The exact number and
             placement of the staples is implementation and/or site-
             defined.
   '10'-'19'   reserved for future generic finishing enum values.

   The following values are more specific; they indicate a corner or an
   edge as if the document were a portrait document (see below):

   '20'   'staple-top-left':  Bind the document(s) with one or more
             staples in the top left corner.
   '21'   'staple-bottom-left':  Bind the document(s) with one or more
             staples in the bottom left corner.
   '22'   'staple-top-right':  Bind the document(s) with one or more
             staples in the top right corner.
   '23'   'staple-bottom-right':  Bind the document(s) with one or more
             staples in the bottom right corner.
   '24'   'edge-stitch-left':  Bind the document(s) with one or more
             staples (wire stitches) along the left edge.  The exact
             number and placement of the staples is implementation
             and/or site-defined.





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   '25'   'edge-stitch-top':  Bind the document(s) with one or more
             staples (wire stitches) along the top edge.  The exact
             number and placement of the staples is implementation
             and/or site-defined.
   '26'   'edge-stitch-right':  Bind the document(s) with one or more
             staples (wire stitches) along the right edge.  The exact
             number and placement of the staples is implementation
             and/or site-defined.
   '27'   'edge-stitch-bottom':  Bind the document(s) with one or more
             staples (wire stitches) along the bottom edge.  The exact
             number and placement of the staples is implementation
             and/or site-defined.
   '28'   'staple-dual-left':  Bind the document(s) with two staples
             (wire stitches) along the left edge assuming a portrait
             document (see above).
   '29'   'staple-dual-top':  Bind the document(s) with two staples
             (wire stitches) along the top edge assuming a portrait
             document (see above).
   '30'   'staple-dual-right':  Bind the document(s) with two staples
             (wire stitches) along the right edge assuming a portrait
             document (see above).
   '31'   'staple-dual-bottom':  Bind the document(s) with two staples
             (wire stitches) along the bottom edge assuming a portrait
             document (see above).

   The 'staple-xxx' values are specified with respect to the document as
   if the document were a portrait document.  If the document is
   actually a landscape or a reverse-landscape document, the client
   supplies the appropriate transformed value.  For example, to position
   a staple in the upper left hand corner of a landscape document when
   held for reading, the client supplies the 'staple-bottom-left' value
   (since landscape is defined as a +90 degree rotation of the image
   with respect to the media from portrait, i.e., anti-clockwise).  On
   the other hand, to position a staple in the upper left hand corner of
   a reverse-landscape document when held for reading, the client
   supplies the 'staple-top-right' value (since reverse-landscape is
   defined as a -90 degree rotation of the image with respect to the
   media from portrait, i.e., clockwise).

   The angle (vertical, horizontal, angled) of each staple with respect
   to the document depends on the implementation which may in turn
   depend on the value of the attribute.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.



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   If the client supplies a value of 'none' along with any other
   combination of values, it is the same as if only that other
   combination of values had been supplied (that is the 'none' value has
   no effect).

4.2.7 page-ranges (1setOf rangeOfInteger (1:MAX))



   This attribute identifies the range(s) of print-stream pages that the
   Printer object uses for each copy of each document which are to be
   printed.  Nothing is printed for any pages identified that do not
   exist in the document(s).  Ranges MUST be in ascending order, for
   example: 1-3, 5-7, 15-19 and MUST NOT overlap, so that a non-spooling
   Printer object can process the job in a single pass.  If the ranges
   are not ascending or are overlapping, the IPP object MUST reject the
   request and return the 'client-error-bad-request' status code.  The
   attribute is associated with print-stream pages not application-
   numbered pages (for example, the page numbers found in the headers
   and or footers for certain word processing applications).

   For Jobs with multiple documents, the "multiple-document-handling"
   attribute determines what constitutes a "copy" for purposes of the
   specified page range(s).  When "multiple-document-handling" is
   'single-document', the Printer object MUST apply each supplied page
   range once to the concatenation of the print-stream pages.  For
   example, if there are 8 documents of 10 pages each, the page-range
   '41:60' prints the pages in the 5th and 6th documents as a single
   document and none of the pages of the other documents are printed.
   When "multiple-document- handling" is 'separate-documents-
   uncollated-copies' or 'separate-documents-collated-copies', the
   Printer object MUST apply each supplied page range repeatedly to each
   document copy.  For the same job, the page-range '1:3, 10:10' would
   print the first 3 pages and the 10th page of each of the 8 documents
   in the Job, as 8 separate documents.

   In most cases, the exact pages to be printed will be generated by a
   device driver and this attribute would not be required.  However,
   when printing an archived document which has already been formatted,
   the end user may elect to print just a subset of the pages contained
   in the document.  In this case, if page-range = n.m is specified, the
   first page to be printed will be page n. All subsequent pages of the
   document will be printed through and including page m.

   "page-ranges-supported" is a boolean value indicating whether or not
   the printer is capable of supporting the printing of page ranges.
   This capability may differ from one PDL to another. There is no
   "page-ranges-default" attribute.  If the "page-ranges" attribute is
   not supplied by the client, all pages of the document will be
   printed.



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   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.8 sides (type2 keyword)



   This attribute specifies how print-stream pages are to be imposed
   upon the sides of an instance of a selected medium, i.e., an
   impression.

   The standard keyword values are:

      'one-sided': imposes each consecutive print-stream page upon the
         same side of consecutive media sheets.
      'two-sided-long-edge': imposes each consecutive pair of print-
         stream pages upon front and back sides of consecutive media
         sheets, such that the orientation of each pair of print-stream
         pages on the medium would be correct for the reader as if for
         binding on the long edge.  This imposition is sometimes called
         'duplex' or 'head-to-head'.
      'two-sided-short-edge': imposes each consecutive pair of print-
         stream pages upon front and back sides of consecutive media
         sheets, such that the orientation of each pair of print-stream
         pages on the medium would be correct for the reader as if for
         binding on the short edge.  This imposition is sometimes called
         'tumble' or 'head-to-toe'.
      'two-sided-long-edge', 'two-sided-short-edge',
         'tumble', and 'duplex' all work the same for portrait or
         landscape.  However
         'head-to-toe' is
      'tumble' in portrait but 'duplex' in landscape.  'head-to-head'
         also switches between 'duplex' and 'tumble' when using portrait
         and landscape modes.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.9 number-up (integer(1:MAX))



   This attribute specifies the number of print-stream pages to impose
   upon a single side of an instance of a selected medium.  For example,
   if the value is:




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   Value  Description

   '1'    the Printer MUST place one print-stream page on a single side
             of an instance of the selected medium (MAY add some sort
             of translation, scaling, or rotation).
   '2'    the Printer MUST place two print-stream pages on a single side
             of an instance of the selected medium (MAY add some sort
             of translation, scaling, or rotation).
   '4'    the Printer MUST place four print-stream pages on a single
             side of an instance of the selected medium (MAY add some
             sort of translation, scaling, or rotation).

   This attribute primarily controls the translation, scaling and
   rotation of print-stream pages.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.10 orientation-requested (type2 enum)



   This attribute indicates the desired orientation for printed print-
   stream pages; it does not describe the orientation of the client-
   supplied print-stream pages.

   For some document formats (such as 'application/postscript'), the
   desired orientation of the print-stream pages is specified within the
   document data.  This information is generated by a device driver
   prior to the submission of the print job.  Other document formats
   (such as 'text/plain') do not include the notion of desired
   orientation within the document data.  In the latter case it is
   possible for the Printer object to bind the desired orientation to
   the document data after it has been submitted.  It is expected that a
   Printer object would only support "orientations-requested" for some
   document formats (e.g., 'text/plain' or 'text/html') but not others
   (e.g., 'application/postscript').  This is no different than any
   other Job Template attribute since section 4.2, item 1, points out
   that a Printer object may support or not support any Job Template
   attribute based on the document format supplied by the client.
   However, a special mention is made here since it is very likely that
   a Printer object will support "orientation-requested" for only a
   subset of the supported document formats.







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   Standard enum values are:

   Value  Symbolic Name and Description

   '3'    'portrait':  The content will be imaged across the short edge
             of the medium.
   '4'    'landscape':  The content will be imaged across the long edge
             of the medium.  Landscape is defined to be a rotation of
             the print-stream page to be imaged by +90 degrees with
             respect to the medium (i.e. anti-clockwise) from the
             portrait orientation.  Note:  The +90 direction was
             chosen because simple finishing on the long edge is the
             same edge whether portrait or landscape
   '5'    'reverse-landscape':  The content will be imaged across the
             long edge of the medium.  Reverse-landscape is defined to
             be a rotation of the print-stream page to be imaged by -
             90 degrees with respect to the medium (i.e. clockwise)
             from the portrait orientation.  Note: The 'reverse-
             landscape' value was added because some applications
             rotate landscape -90 degrees from portrait, rather than
             +90 degrees.
   '6'    'reverse-portrait':  The content will be imaged across the
             short edge of the medium.  Reverse-portrait is defined to
             be a rotation of the print-stream page to be imaged by
             180 degrees with respect to the medium from the portrait
             orientation.  Note: The 'reverse-portrait' value was
             added for use with the "finishings" attribute in cases
             where the opposite edge is desired for finishing a
             portrait document on simple finishing devices that have
             only one finishing position.  Thus a 'text'/plain'
             portrait document can be stapled "on the right" by a
             simple finishing device as is common use with some middle
             eastern languages such as Hebrew.

   Note: The effect of this attribute on jobs with multiple documents is
   controlled by the "multiple-document-handling" job attribute (section
   4.2.4) and the relationship of this attribute and the other
   attributes that control document processing is described in section
   15.3.

4.2.11 media (type3 keyword | name(MAX))



   This attribute identifies the medium that the Printer uses for all
   impressions of the Job.

   The values for "media" include medium-names, medium-sizes, input-
   trays and electronic forms so that one attribute specifies the media.
   If a Printer object supports a medium name as a value of this



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   attribute, such a medium name implicitly selects an input-tray that
   contains the specified medium.  If a Printer object supports a medium
   size as a value of this attribute, such a medium size implicitly
   selects a medium name that in turn implicitly selects an input-tray
   that contains the medium with the specified size.  If a Printer
   object supports an input-tray as the value of this attribute, such an
   input-tray implicitly selects the medium that is in that input-tray
   at the time the job prints.  This case includes manual-feed input-
   trays.  If a Printer object supports an electronic form as the value
   of this attribute, such an electronic form implicitly selects a
   medium-name that in turn implicitly selects an input-tray that
   contains the medium specified by the electronic form.  The electronic
   form also implicitly selects an image that the Printer MUST merge
   with the document data as its prints each page.

   Standard keyword values are taken from ISO DPA [ISO10175], the
   Printer MIB [RFC1759], and ASME-Y14.1M [ASME-Y14.1M] and are listed
   in section 14.  An administrator MAY define additional values using
   the 'name' or 'keyword' attribute syntax, depending on
   implementation.

   There is also an additional Printer attribute named "media-ready"
   which differs from "media-supported" in that legal values only
   include the subset of "media-supported" values that are physically
   loaded and ready for printing with no operator intervention required.
   If an IPP object supports "media-supported", it NEED NOT support
   "media-ready".

   The relationship of this attribute and the other attributes that
   control document processing is described in section 15.3.

4.2.12 printer-resolution (resolution)



   This attribute identifies the resolution that Printer uses for the
   Job.

4.2.13 print-quality (type2 enum)



   This attribute specifies the print quality that the Printer uses for
   the Job.

   The standard enum values are:

   Value  Symbolic Name and Description

   '3'    'draft': lowest quality available on the printer
   '4'    'normal': normal or intermediate quality on the printer
   '5'    'high': highest quality available on the printer



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4.3 Job Description Attributes



   The attributes in this section form the attribute group called "job-
   description".  The following table summarizes these attributes.  The
   third column indicates whether the attribute is a REQUIRED attribute
   that MUST be supported by Printer objects.  If it is not indicated as
   REQUIRED, then it is OPTIONAL.  The maximum size in octets for 'text'
   and 'name' attributes is indicated in parenthesizes.

   +----------------------------+----------------------+--------------+
   |      Attribute             |     Syntax           |   REQUIRED?  |
   +----------------------------+----------------------+--------------+
   | job-uri                    | uri                  |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-id                     | integer(1:MAX)       |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-printer-uri            | uri                  |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-more-info              | uri                  |              |
   +----------------------------+----------------------+--------------+
   | job-name                   | name (MAX)           |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-originating-user-name  | name (MAX)           |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-state                  | type1 enum           |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-state-reasons          | 1setOf type2 keyword |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-state-message          | text (MAX)           |              |
   +----------------------------+----------------------+--------------+
   | job-detailed-status-       | 1setOf text (MAX)    |              |
   |       messages             |                      |              |
   +----------------------------+----------------------+--------------+
   | job-document-access-errors | 1setOf text (MAX)    |              |
   +----------------------------+----------------------+--------------+
   | number-of-documents        | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | output-device-assigned     | name (127)           |              |
   +----------------------------+----------------------+--------------+
   | time-at-creation           | integer (MIN:MAX)    |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | time-at-processing         | integer (MIN:MAX)    |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | time-at-completed          | integer (MIN:MAX)    |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | job-printer-up-time        | integer (1:MAX)      |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | date-time-at-creation      | dateTime             |              |



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   +----------------------------+----------------------+--------------+
   | date-time-at-processing    | dateTime             |              |
   +----------------------------+----------------------+--------------+
   | date-time-at-completed     | dateTime             |              |
   +----------------------------+----------------------+--------------+
   | number-of-intervening-jobs | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | job-message-from-operator  | text (127)           |              |
   +----------------------------+----------------------+--------------+
   | job-k-octets               | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | job-impressions            | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | job-media-sheets           | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | job-k-octets-processed     | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | job-impressions-completed  | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | job-media-sheets-completed | integer (0:MAX)      |              |
   +----------------------------+----------------------+--------------+
   | attributes-charset         | charset              |  REQUIRED    |
   +----------------------------+----------------------+--------------+
   | attributes-natural-language| naturalLanguage      |  REQUIRED    |
   +----------------------------+----------------------+--------------+

4.3.1 job-uri (uri)



   This REQUIRED attribute contains the URI for the job.  The Printer
   object, on receipt of a new job, generates a URI which identifies the
   new Job.  The Printer object returns the value of the "job-uri"
   attribute as part of the response to a create request.  The precise
   format of a Job URI is implementation dependent.  If the Printer
   object supports more than one URI and there is some relationship
   between the newly formed Job URI and the Printer object's URI, the
   Printer object uses the Printer URI supplied by the client in the
   create request.  For example, if the create request comes in over a
   secure channel, the new Job URI MUST use the same secure channel.
   This can be guaranteed because the Printer object is responsible for
   generating the Job URI and the Printer object is aware of its
   security configuration and policy as well as the Printer URI used in
   the create request.

   For a description of this attribute and its relationship to "job-id"
   and "job-printer-uri" attribute, see the discussion in section 2.4 on
   "Object Identity".





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4.3.2 job-id (integer(1:MAX))



   This REQUIRED attribute contains the ID of the job.  The Printer, on
   receipt of a new job, generates an ID which identifies the new Job on
   that Printer.  The Printer returns the value of the "job-id"
   attribute as part of the response to a create request.  The 0 value
   is not included to allow for compatibility with SNMP index values
   which also cannot be 0.

   For a description of this attribute and its relationship to "job-uri"
   and "job-printer-uri" attribute, see the discussion in section 2.4 on
   "Object Identity".

4.3.3 job-printer-uri (uri)



   This REQUIRED attribute identifies the Printer object that created
   this Job object.  When a Printer object creates a Job object, it
   populates this attribute with the Printer object URI that was used in
   the create request.  This attribute permits a client to identify the
   Printer object that created this Job object when only the Job
   object's URI is available to the client.  The client queries the
   creating Printer object to determine which languages, charsets,
   operations, are supported for this Job.

   For a description of this attribute and its relationship to "job-uri"
   and "job-id" attribute, see the discussion in section 2.4 on "Object
   Identity".

4.3.4 job-more-info (uri)



   Similar to "printer-more-info", this attribute contains the URI
   referencing some resource with more information about this Job
   object, perhaps an HTML page containing information about the Job.

4.3.5 job-name (name(MAX))



   This REQUIRED attribute is the name of the job.  It is a name that is
   more user friendly than the "job-uri" attribute value.  It does not
   need to be unique between Jobs.  The Job's "job-name" attribute is
   set to the value supplied by the client in the "job-name" operation
   attribute in the create request (see Section 3.2.1.1).   If, however,
   the "job-name" operation attribute is not supplied by the client in
   the create request, the Printer object, on creation of the Job, MUST
   generate a name.  The printer SHOULD generate the value of the Job's
   "job-name" attribute from the first of the following sources that
   produces a value: 1) the "document-name" operation attribute of the





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   first (or only) document, 2) the "document-URI" attribute of the
   first (or only) document, or 3) any other piece of Job specific
   and/or Document Content information.

4.3.6 job-originating-user-name (name(MAX))



   This REQUIRED attribute contains the name of the end user that
   submitted the print job.  The Printer object sets this attribute to
   the most authenticated printable name that it can obtain from the
   authentication service over which the IPP operation was received.
   Only if such is not available, does the Printer object use the value
   supplied by the client in the "requesting-user-name" operation
   attribute of the create operation (see Sections 4.4.2, 4.4.3, and 8).

   Note:  The Printer object needs to keep an internal originating user
   id of some form, typically as a credential of a principal, with the
   Job object.  Since such an internal attribute is implementation-
   dependent and not of interest to clients, it is not specified as a
   Job Description attribute.  This originating user id is used for
   authorization checks (if any) on all subsequent operations.

4.3.7 job-state (type1 enum)



   This REQUIRED attribute identifies the current state of the job.
   Even though the IPP protocol defines seven values for job states
   (plus the out-of-band 'unknown' value - see Section 4.1),
   implementations only need to support those states which are
   appropriate for the particular implementation.  In other words, a
   Printer supports only those job states implemented by the output
   device and available to the Printer object implementation.

   Standard enum values are:

   Values Symbolic Name and Description

   '3'  'pending':  The job is a candidate to start processing, but is
           not yet processing.

   '4'  'pending-held':  The job is not a candidate for processing for
           any number of reasons but will return to the 'pending'
           state as soon as the reasons are no longer present.  The
           job's "job-state-reason" attribute MUST indicate why the
           job is no longer a candidate for processing.








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   '5'  'processing':  One or more of:

           1.  the job is using, or is attempting to use, one or
           more purely software processes that are analyzing,
           creating, or interpreting a PDL, etc.,
           2.  the job is using, or is attempting to use, one or
           more hardware devices that are interpreting a PDL, making
           marks on a medium, and/or performing finishing, such as
           stapling, etc.,
           3. the Printer object has made the job ready for
           printing, but the output device is not yet printing it,
           either because the job hasn't reached the output device
           or because the job is queued in the output device or some
           other spooler, awaiting the output device to print it.

           When the job is in the 'processing' state, the entire job
           state includes the detailed status represented in the
           Printer object's "printer-state", "printer-state-
           reasons", and "printer-state-message" attributes.

           Implementations MAY, though they NEED NOT,  include
           additional values in the job's "job-state-reasons"
           attribute to indicate the progress of the job, such as
           adding the 'job-printing' value to indicate when the
           output device is actually making marks on paper and/or
           the 'processing-to-stop-point' value to indicate that the
           IPP object is in the process of canceling or aborting the
           job.  Most implementations won't bother with this nuance.

   '6'  'processing-stopped':  The job has stopped while processing
           for any number of reasons and will return to the
           'processing' state as soon as the reasons are no longer
           present.

           The job's "job-state-reason" attribute MAY indicate why
           the job has stopped processing.  For example, if the
           output device is stopped, the 'printer-stopped' value MAY
           be included in the job's "job-state-reasons" attribute.

           Note:  When an output device is stopped, the device
           usually indicates its condition in human readable form
           locally at the device.  A client can obtain more complete
           device status remotely by querying the Printer object's
           "printer-state", "printer-state-reasons" and "printer-
           state-message" attributes.

   '7'  'canceled':  The job has been canceled by a Cancel-Job
           operation and the Printer object has completed canceling



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           the job and all job status attributes have reached their
           final values for the job.  While the Printer object is
           canceling the job, the job remains in its current state,
           but the job's "job-state-reasons" attribute SHOULD
           contain the 'processing-to-stop-point' value and one of
           the 'canceled-by-user', 'canceled-by-operator', or
           'canceled-at-device' value.  When the job moves to the
           'canceled' state, the  'processing-to-stop-point' value,
           if present, MUST be removed, but the 'canceled-by-xxx',
           if present, MUST remain.

   '8'  'aborted':  The job has been aborted by the system, usually
           while the job was in the 'processing' or 'processing-
           stopped' state and the Printer has completed aborting the
           job and all job status attributes have reached their
           final values for the job.  While the Printer object is
           aborting the job, the job remains in its current state,
           but the job's "job-state-reasons" attribute SHOULD
           contain the 'processing-to-stop-point' and 'aborted-by-
           system' values.  When the job moves to the 'aborted'
           state, the  'processing-to-stop-point' value, if present,
           MUST be removed, but the 'aborted-by-system' value, if
           present, MUST remain.

   '9'  'completed':  The job has completed successfully or with
           warnings or errors after processing and all of the job
           media sheets have been successfully stacked in the
           appropriate output bin(s) and all job status attributes
           have reached their final values for the job.  The job's
           "job-state-reasons" attribute SHOULD contain one of:
           'completed-successfully', 'completed-with-warnings', or
           'completed-with-errors' values.

   The final value for this attribute MUST be one of: 'completed',
   'canceled', or 'aborted' before the Printer removes the job
   altogether.  The length of time that jobs remain in the 'canceled',
   'aborted', and 'completed' states depends on implementation.  See
   section 4.3.7.2.

   The following figure shows the normal job state transitions.

                                                      +----> canceled
                                                     /
       +----> pending --------> processing ---------+------> completed
       |         ^                   ^               \
   --->+         |                   |                +----> aborted
       |         v                   v               /
       +----> pending-held    processing-stopped ---+



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   Normally a job progresses from left to right.  Other state
   transitions are unlikely, but are not forbidden.  Not shown are the
   transitions to the 'canceled' state from the 'pending', 'pending-
   held', and 'processing-stopped' states.

   Jobs reach one of the three terminal states: 'completed', 'canceled',
   or 'aborted', after the jobs have completed all activity, including
   stacking output media, after the jobs have completed all activity,
   and all job status attributes have reached their final values for the
   job.

4.3.7.1 Forwarding Servers



   As with all other IPP attributes, if the implementation cannot
   determine the correct value for this attribute, it SHOULD respond
   with the out-of-band value 'unknown' (see section 4.1) rather than
   try to guess at some possibly incorrect value and give the end user
   the wrong impression about the state of the Job object.  For example,
   if the implementation is just a gateway into some printing system
   from which it can normally get status, but temporarily is unable,
   then the implementation should return the 'unknown' value.  However,
   if the implementation is a gateway to a printing system that never
   provides detailed status about the print job, the implementation MAY
   set the IPP Job object's state  to 'completed', provided that it also
   sets the 'queued-in-device' value in the job's "job-state-reasons"
   attribute (see section 4.3.8).

4.3.7.2 Partitioning of Job States



   This section partitions the 7 job states into phases:  Job Not
   Completed, Job Retention, Job History, and Job Removal.  This section
   also explains the 'job-restartable' value of the "job-state-reasons"
   Job Description attribute for use with the Restart-Job operation.

   Job Not Completed:  When a job is in the 'pending', 'pending-held',
   'processing', or 'processing-stopped' states, the job is not
   completed.

   Job Retention:  When a job enters one of the three terminal job
   states:  'completed', 'canceled', or 'aborted', the IPP Printer
   object MAY "retain" the job in a restartable condition for an
   implementation-defined time period.  This time period MAY be zero
   seconds and MAY depend on the terminal job state.  This phase is
   called Job Retention.  While in the Job Retention phase, the job's
   document data is retained and a client may restart the job using the
   Restart-Job operation.  If the IPP object supports the Restart-Job





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   operation, then it SHOULD indicate that the job is restartable by
   adding the 'job-restartable' value to the job's "job-state-reasons"
   attribute (see Section 4.3.8) during the Job Retention phase.

   Job History:  After the Job Retention phase expires for a job, the
   Printer object deletes the document data for the job and the job
   becomes part of the Job History.  The Printer object MAY also delete
   any number of the job attributes.  Since the job is no longer
   restartable, the Printer object MUST remove the 'job-restartable'
   value from the job's "job-state-reasons" attribute, if present.

   Job Removal:  After the job has remained in the Job History for an
   implementation-defined time, such as when the number of jobs exceeds
   a fixed number or after a fixed time period (which MAY be zero
   seconds), the IPP Printer removes the job from the system.

   Using the Get-Jobs operation and supplying the 'not-completed' value
   for the "which-jobs" operation attribute, a client is requesting jobs
   in the Job Not Completed phase.  Using the Get-Jobs operation and
   supplying the 'completed' value for the "which-jobs" operation
   attribute, a client is requesting jobs in the Job Retention and Job
   History phases.  Using the Get-Job-Attributes operation, a client is
   requesting a job in any phase except Job Removal.  After Job Removal,
   the Get-Job-Attributes and Get-Jobs operations no longer are capable
   of returning any information about a job.

4.3.8 job-state-reasons (1setOf type2 keyword)



   This REQUIRED attribute provides additional information about the
   job's current state, i.e., information that augments the value of the
   job's "job-state" attribute.

   These values MAY be used with any job state or states for which the
   reason makes sense.  Some of these value definitions indicate
   conformance requirements; the rest are OPTIONAL.  Furthermore, when
   implemented, the Printer MUST return these values when the reason
   applies and MUST NOT return them when the reason no longer applies
   whether the value of the Job's "job-state" attribute changed or not.
   When the Job does not have any reasons for being in its current
   state, the value of the Job's "job-state-reasons" attribute MUST be
   'none'.

   Note: While values cannot be added to the 'job-state' attribute
   without impacting deployed clients that take actions upon receiving
   "job-state" values, it is the intent that additional "job-state-
   reasons" values can be defined and registered without impacting such
   deployed clients.  In other words, the "job-state-reasons" attribute
   is intended to be extensible.



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   The following standard keyword values are defined.  For ease of
   understanding, the values are presented in the order in which the
   reasons are likely to occur (if implemented), starting with the
   'job-incoming' value:

      'none':  There are no reasons for the job's current state.  This
         state reason is semantically equivalent to "job-state-reasons"
         without any value and MUST be used when there is no other
         value, since the 1setOf attribute syntax requires at least one
         value.
      'job-incoming':  Either (1) the Printer has accepted the Create-
         Job operation and is expecting additional Send-Document and/or
         Send-URI operations, or (2) the Printer is retrieving/accepting
         document data as a result of a Print-Job, Print-URI, Send-
         Document or Send-URI operation.
      'job-data-insufficient':  The Create-Job operation has been
         accepted by the Printer, but the Printer is expecting
         additional document data before it can move the job into the
         'processing' state.  If a Printer starts processing before it
         has received all data, the Printer removes the 'job-data-
         insufficient' reason, but the 'job-incoming' remains.  If a
         Printer starts processing after it has received all data, the
         Printer removes the 'job-data-insufficient' reason and the
         'job-incoming' at the same time.
      'document-access-error':  After accepting a Print-URI or Send-URI
         request, the Printer could not access one or more documents
         passed by reference.  This reason is intended to cover any file
         access problem, including file does not exist and access denied
         because of an access control problem.  The Printer MAY also
         indicate the document access error using the "job-document-
         access-errors" Job Description attribute (see section 4.3.11).
         Whether the Printer aborts the job and moves the job to the
         'aborted' job state or prints all documents that are accessible
         and moves the job to the 'completed' job state and adds the
         'completed-with-errors' value in the job's "job-state-reasons"
         attribute depends on implementation and/or site policy.  This
         value SHOULD be supported if the Print-URI or Send-URI
         operations are supported.
      'submission-interrupted':  The job was not completely submitted
         for some unforeseen reason, such as: (1) the Printer has
         crashed before the job was closed by the client, (2) the
         Printer or the document transfer method has crashed in some
         non-recoverable way before the document data was entirely
         transferred to the Printer, (3) the client crashed or failed to
         close the job before the time-out period.  See section 4.4.31.
      'job-outgoing':  The Printer is transmitting the job to the output
         device.




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      'job-hold-until-specified':  The value of the job's "job-hold-
         until" attribute was specified with a time period that is still
         in the future.  The job MUST NOT be a candidate for processing
         until this reason is removed and there are no other reasons to
         hold the job.  This value SHOULD be supported if the "job-
         hold-until" Job Template attribute is supported.
      'resources-are-not-ready':  At least one of the resources needed
         by the job, such as media, fonts, resource objects, etc., is
         not ready on any of the physical printer's for which the job is
         a candidate.  This condition MAY be detected when the job is
         accepted, or subsequently while the job is pending or
         processing, depending on implementation.  The job may remain in
         its current state or be moved to the 'pending-held' state,
         depending on implementation and/or job scheduling policy.
      'printer-stopped-partly':  The value of the Printer's "printer-
         state-reasons" attribute contains the value 'stopped-partly'.
      'printer-stopped':  The value of the Printer's "printer-state"
         attribute is 'stopped'.
      'job-interpreting': Job is in the 'processing' state, but more
         specifically, the Printer is interpreting the document data.
      'job-queued': Job is in the 'processing' state, but more
         specifically, the Printer has queued the document data.
      'job-transforming': Job is in the 'processing' state, but more
         specifically, the Printer is interpreting document data and
         producing another electronic representation.
      'job-queued-for-marker': Job is in any of the 'pending-held',
         'pending', or 'processing' states, but more specifically, the
         Printer has completed enough processing of the document to be
         able to start marking and the job is waiting for the marker.
         Systems that require human intervention to release jobs using
         the Release-Job operation, put the job into the 'pending-held'
         job state.  Systems that automatically select a job to use the
         marker put the job into the  'pending' job state or keep the
         job in the 'processing' job state while waiting for the marker,
         depending on implementation.  All implementations put the job
         into (or back into) the 'processing' state when marking does
         begin.
      'job-printing':  The output device is marking media. This value is
         useful for Printers which spend a great deal of time processing
         (1) when no marking is happening and then want to show that
         marking is now happening or (2) when the job is in the process
         of being canceled or aborted while the job remains in the
         'processing' state, but the marking has not yet stopped so that
         impression or sheet counts are still increasing for the job.







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      'job-canceled-by-user':  The job was canceled by the owner of the
         job using the Cancel-Job request, i.e., by a user whose
         authenticated identity is the same as the value of the
         originating user that created the Job object, or by some other
         authorized end-user, such as a member of the job owner's
         security group.  This value SHOULD be supported.
      'job-canceled-by-operator':  The job was canceled by the operator
         using the Cancel-Job request, i.e., by a user who has been
         authenticated as having operator privileges (whether local or
         remote).  If the security policy is to allow anyone to cancel
         anyone's job, then this value may be used when the job is
         canceled by other than the owner of the job.  For such a
         security policy, in effect, everyone is an operator as far as
         canceling jobs with IPP is concerned.  This value SHOULD be
         supported if the implementation permits canceling by other than
         the owner of the job.
      'job-canceled-at-device':  The job was canceled by an unidentified
         local user, i.e., a user at a console at the device.  This
         value SHOULD be supported if the implementation supports
         canceling jobs at the console.
      'aborted-by-system':  The job (1) is in the process of being
         aborted, (2) has been aborted by the system and placed in the
         'aborted' state, or (3) has been aborted by the system and
         placed in the 'pending-held' state, so that a user or operator
         can manually try the job again.  This value SHOULD be
         supported.
      'unsupported-compression': The job was aborted by the system
         because the Printer determined while attempting to decompress
         the document-data's that the compression is actually not among
         those supported by the Printer.  This value MUST be supported,
         since "compressions is a REQUIRED operation attribute.
      'compression-error': The job was aborted by the system because the
         Printer encountered an error in the document-data while
         decompressing it.  If the Printer posts this reason, the
         document-data has already passed any tests that would have led
         to the 'unsupported-compression' job-state-reason.
      'unsupported-document-format': The job was aborted by the system
         because the document-data's document-format is not among those
         supported by the Printer.  If the client specifies the
         document-format as 'application/octet-stream', the printer MAY
         abort the job and post this reason even though the format is a
         member of the "document-format-supported" printer attribute,
         but not among the auto-sensed document-formats.  This value
         MUST be supported, since "document-format" is a REQUIRED
         operation attribute.






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      'document-format-error': The job was aborted by the system because
         the Printer encountered an error in the document-data while
         processing it.  If the Printer posts this reason, the
         document-data has already passed any tests that would have led
         to the 'unsupported-document-format' job-state-reason.
      'processing-to-stop-point':  The requester has issued a Cancel-Job
         operation or the Printer object has aborted the job, but is
         still performing some actions on the job until a specified stop
         point occurs or job termination/cleanup is completed.

         If the implementation requires some measurable time to cancel
         the job in the 'processing' or 'processing-stopped' job states,
         the IPP object MUST use this value to indicate that the Printer
         object is still performing some actions on the job while the
         job remains in the 'processing' or 'processing-stopped' state.
         After all the job's job description attributes have stopped
         incrementing, the Printer object moves the job from the
         'processing' state to the 'canceled' or
         'aborted' job states.

      'service-off-line':  The Printer is off-line and accepting no
         jobs.  All 'pending' jobs are put into the 'pending-held'
         state.  This situation could be true if the service's or
         document transform's input is impaired or broken.
      'job-completed-successfully':  The job completed successfully.
         This value SHOULD be supported.
      'job-completed-with-warnings':  The job completed with warnings.
         This value SHOULD be supported if the implementation detects
         warnings.
      'job-completed-with-errors':  The job completed with errors (and
         possibly warnings too).  This value SHOULD be supported if the
         implementation detects errors.
      'job-restartable' - This job is retained (see section 4.3.7.2) and
         is currently able to be restarted using the Restart-Job
         operation (see section 3.3.7).  If 'job-restartable' is a value
         of the job's 'job-state-reasons' attribute, then the IPP object
         MUST accept a Restart-Job operation for that job.  This value
         SHOULD be supported if the Restart-Job operation is supported.
      'queued-in-device': The job has been forwarded to a device or
         print system that is unable to send back status.  The Printer
         sets the job's "job-state " attribute to 'completed'  and adds
         the 'queued-in-device' value to the job's "job-state-reasons"
         attribute to indicate that the Printer has no additional
         information about the job and never will have any better
         information.  See section 4.3.7.1.






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4.3.9 job-state-message (text(MAX))



   This attribute specifies information about the "job-state" and "job-
   state-reasons" attributes in human readable text.  If the Printer
   object supports this attribute, the Printer object MUST be able to
   generate this message in any of the natural languages identified by
   the Printer's "generated-natural-language-supported" attribute (see
   the "attributes-natural-language" operation attribute specified in
   Section 3.1.4.1).

   The value SHOULD NOT contain additional information not contained in
   the values of the "job-state" and "job-states-reasons" attributes,
   such as interpreter error information.  Otherwise, application
   programs might attempt to parse the (localized text).  For such
   additional information such as interpreter errors for application
   program consumption or specific document access errors, new
   attributes with keyword values, needs to be developed and registered.

4.3.10 job-detailed-status-messages (1setOf text(MAX))



   This attribute specifies additional detailed and technical
   information about the job.  The Printer NEED NOT localize the
   message(s), since they are intended for use by the system
   administrator or other experienced technical persons.  Localization
   might obscure the technical meaning of such messages.  Clients MUST
   NOT
attempt to parse the value of this attribute.  See "job-
   document-access-errors" (section 4.3.11) for additional errors that a
   program can process.

4.3.11 job-document-access-errors (1setOf text(MAX))



   This attribute provides additional information about each document
   access error for this job encountered by the Printer after it
   returned a response to the Print-URI or Send-URI operation and
   subsequently attempted to access document(s) supplied in the Print-
   URI or Send-URI operation.  For errors in the protocol that is
   identified by the URI scheme in the "document-uri" operation
   attribute, such as 'http:' or 'ftp:', the error code is returned in
   parentheses, followed by the URI.  For example:

      (404) http://ftp.pwg.org/pub/pwg/ipp/new_MOD/ipp-model-v11.pdf

   Most Internet protocols use decimal error codes (unlike IPP), so the
   ASCII error code representation is in decimal.







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4.3.12 number-of-documents (integer(0:MAX))



   This attribute indicates the number of documents in the job, i.e.,
   the number of Send-Document, Send-URI, Print-Job, or Print-URI
   operations that the Printer has accepted for this job, regardless of
   whether the document data has reached the Printer object or not.

   Implementations supporting the OPTIONAL Create-Job/Send-
   Document/Send-URI operations SHOULD support this attribute so that
   clients can query the number of documents in each job.

4.3.13 output-device-assigned (name(127))



   This attribute identifies the output device to which the Printer
   object has assigned this job.  If an output device implements an
   embedded Printer object, the Printer object NEED NOT set this
   attribute.  If a print server implements a Printer object, the value
   MAY be empty (zero- length string) or not returned until the Printer
   object assigns an output device to the job.  This attribute is
   particularly useful when a single Printer object supports multiple
   devices (so called "fan-out" - see section 2.1).

4.3.14 Event Time Job Description Attributes



   This section defines the Job Description attributes that indicate the
   time at which certain events occur for a job.  If the job event has
   not yet occurred, then the IPP object MUST return the 'no-value'
   out-of-band value (see the beginning of Section 4.1).  The "time-at-
   xxx(integer)" attributes represent time as an 'integer' representing
   the number of seconds since the device was powered up (informally
   called "time ticks").  The "date-time-at-xxx(dateTime)" attributes
   represent time as 'dateTime' representing date and time (including an
   offset from UTC).

   In order to populate these attributes, the Printer object copies the
   value(s) of the following Printer Description attributes at the time
   the event occurs:

      1. the value in the Printer's "printer-up-time" attribute for the
         "time-at-xxx(integer)" attributes

      2. the value in the Printer's "printer-current-time" attribute for
         the "date-time-at-xxx(dateTime)" attributes.

   If the Printer resets its "printer-up-time" attribute to 1 on power-
   up (see section 4.4.29) and has persistent jobs, then it MUST change
   all of jobs' "time-at-xxx(integer)" (time tick) job attributes whose
   events have occurred either to:



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      1. 0 to indicate that the event happened before the most recent
         power up OR

      2. the negative of the number of seconds before the most recent
         power-up that the event took place, though the negative number
         NEED NOT reflect the exact number of seconds.

   If a client queries a "time-at-xxx(integer)" time tick Job attribute
   and finds the value to be 0 or negative, the client MUST assume that
   the event occurred in some life other than the Printer's current
   life.

   Note: A Printer does not change the values of any "date-time-at-
   xxx(dateTime)" job attributes on power-up.

4.3.14.1 time-at-creation (integer(MIN:MAX))



   This REQUIRED attribute indicates the time at which the Job object
   was created.

4.3.14.2 time-at-processing (integer(MIN:MAX))



   This REQUIRED attribute indicates the time at which the Job object
   first began processing after the create operation or the most recent
   Restart-Job operation.  The out-of-band 'no-value' value is returned
   if the job has not yet been in the 'processing' state (see the
   beginning of Section 4.1).

4.3.14.3 time-at-completed (integer(MIN:MAX))



   This REQUIRED attribute indicates the time at which the Job object
   completed (or was canceled or aborted).  The out-of-band 'no-value'
   value is returned if the job has not yet completed, been canceled, or
   aborted (see the beginning of Section 4.1).

4.3.14.4 job-printer-up-time (integer(1:MAX))



   This REQUIRED Job Description attribute indicates the amount of time
   (in seconds) that the Printer implementation has been up and running.
   This attribute is an alias for the "printer-up-time" Printer
   Description attribute (see Section 4.4.29).

   A client MAY request this attribute in a Get-Job-Attributes or Get-
   Jobs request and use the value returned in combination with other
   requested Event Time Job Description Attributes in order to display
   time attributes to a user.  The difference between this attribute and
   the 'integer' value of a "time-at-xxx" attribute is the number of




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   seconds ago that the "time-at-xxx" event occurred.  A client can
   compute the wall-clock time at which the "time-at-xxx" event occurred
   by subtracting this difference from the client's wall-clock time.

4.3.14.5 date-time-at-creation (dateTime)



   This attribute indicates the date and time at which the Job object
   was created.

4.3.14.6 date-time-at-processing (dateTime)



   This attribute indicates the date and time at which the Job object
   first began processing after the create operation or the most recent
   Restart-Job operation.

4.3.14.7 date-time-at-completed (dateTime)



   This attribute indicates the date and time at which the Job object
   completed (or was canceled or aborted).

4.3.15 number-of-intervening-jobs (integer(0:MAX))



   This attribute indicates the number of jobs that are "ahead" of this
   job in the relative chronological order of expected time to complete
   (i.e., the current scheduled order). For efficiency, it is only
   necessary to calculate this value when an operation is performed that
   requests this attribute.

4.3.16 job-message-from-operator (text(127))



   This attribute provides a message from an operator, system
   administrator or "intelligent" process to indicate to the end user
   the reasons for modification or other management action taken on a
   job.

4.3.17 Job Size Attributes



   This sub-section defines job attributes that describe the size of the
   job.  These attributes are not intended to be counters; they are
   intended to be useful routing and scheduling information if known.
   For these attributes, the Printer object may try to compute the value
   if it is not supplied in the create request.  Even if the client does
   supply a value for these three attributes in the create request, the
   Printer object MAY choose to change the value if the Printer object
   is able to compute a value which is more accurate than the client
   supplied value.  The Printer object may be able to determine the
   correct value for these attributes either right at job submission
   time or at any later point in time.



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4.3.17.1 job-k-octets (integer(0:MAX))



   This attribute specifies the total size of the document(s) in K
   octets, i.e., in units of 1024 octets requested to be processed in
   the job.  The value MUST be rounded up, so that a job between 1 and
   1024 octets MUST be indicated as being 1, 1025 to 2048 MUST be 2,
   etc.

   This value MUST NOT include the multiplicative factors contributed by
   the number of copies specified by the "copies" attribute, independent
   of whether the device can process multiple copies without making
   multiple passes over the job or document data and independent of
   whether the output is collated or not.  Thus the value is independent
   of the implementation and indicates the size of the document(s)
   measured in K octets independent of the number of copies.

   This value MUST also not include the multiplicative factor due to a
   copies instruction embedded in the document data.  If the document
   data actually includes replications of the document data, this value
   will include such replication.  In other words, this value is always
   the size of the source document data, rather than a measure of the
   hardcopy output to be produced.

4.3.17.2 job-impressions (integer(0:MAX))



   This attribute specifies the total size in number of impressions of
   the document(s) being submitted (see the definition of impression in
   section 12.2.5).

   As with "job-k-octets", this value MUST NOT include the
   multiplicative factors contributed by the number of copies specified
   by the "copies" attribute, independent of whether the device can
   process multiple copies without making multiple passes over the job
   or document data and independent of whether the output is collated or
   not.  Thus the value is independent of the implementation and
   reflects the size of the document(s) measured in impressions
   independent of the number of copies.

   As with "job-k-octets", this value MUST also not include the
   multiplicative factor due to a copies instruction embedded in the
   document data.  If the document data actually includes replications
   of the document data, this value will include such replication.  In
   other words, this value is always the number of impressions in the
   source document data, rather than a measure of the number of
   impressions to be produced by the job.






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4.3.17.3 job-media-sheets (integer(0:MAX))



   This attribute specifies the total number of media sheets to be
   produced for this job.

   Unlike the "job-k-octets" and the "job-impressions" attributes, this
   value MUST include the multiplicative factors contributed by the
   number of copies specified by the "copies" attribute and a 'number of
   copies' instruction embedded in the document data, if any.  This
   difference allows the system administrator to control the lower and
   upper bounds of both (1) the size of the document(s) with "job-k-
   octets-supported" and "job-impressions-supported" and (2) the size of
   the job with "job-media-sheets-supported".

4.3.18 Job Progress Attributes



   This sub-section defines job attributes that describe the progress of
   the job.  These attributes are intended to be counters