Internet Printing Protocol/1.1: Encoding and Transport
draft-ietf-ipp-protocol-v11-06

Versions: 00 01 02 03 04 05 06 rfc2910                   Standards Track
INTERNET-DRAFT                                   Robert Herriot (editor)
<draft-ietf-ipp-protocol-v11-06.txt>                   Xerox Corporation
                                                           Sylvan Butler
                                                         Hewlett-Packard
                                                              Paul Moore
                                             Peerless Systems Networking
                                                            Randy Turner
                                                               2wire.com
                                                               John Wenn
                                                       Xerox Corporation
                                                            May 30, 2000


         Internet Printing Protocol/1.1: Encoding and Transport
    Copyright (C) The Internet Society (2000). All Rights Reserved.



Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of [RFC2026].  Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, and
its working groups.  Note that other groups may also distribute working
documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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or to cite them other than as "work in progress".

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed as
http://www.ietf.org/shadow.html.

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 defines the rules for encoding IPP
operations and IPP attributes into 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



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"application/ipp". This document defines a new scheme named 'ipp' for
identifying IPP printers and jobs.

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 [ipp-mod]
   Internet Printing Protocol/1.1: Encoding and Transport (this
   document)
   Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig]
   Mapping between LPD and IPP Protocols [RFC2569]

The document, "Design Goals for an Internet Printing Protocol", 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/1.1. A few OPTIONAL operator operations have been added
to IPP/1.1.

The document, "Rationale for the Structure and Model and Protocol for
the Internet Printing Protocol", 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 document, "Internet Printing Protocol/1.1: Model and Semantics",
describes a simplified model with abstract objects, their attributes,
and their operations that are independent of encoding and transport. It
introduces a Printer and a Job object. The Job object optionally
supports multiple documents per Job. It also addresses security,
internationalization, and directory issues.

The document "Internet Printing Protocol/1.1: Implementer's Guide",
gives advice to implementers of IPP clients and IPP objects.

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








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                           Table of Contents

1. Introduction .......................................................5
2. Conformance Terminology ............................................5
3. Encoding of  the Operation Layer ...................................5
   3.1  Picture of the Encoding .......................................6
      3.1.1 Request and Response.......................................6
      3.1.2 Attribute Group............................................7
      3.1.3 Attribute..................................................8
      3.1.4 Picture of the Encoding of an Attribute-with-one-value.....8
      3.1.5 Additional-value...........................................9
      3.1.6 Alternative Picture of the Encoding of a Request Or a
      Response.........................................................9
   3.2  Syntax of Encoding ...........................................10
   3.3  Attribute-group ..............................................12
   3.4  Required Parameters ..........................................13
      3.4.1 Version-number............................................13
      3.4.2 Operation-id..............................................13
      3.4.3 Status-code...............................................13
      3.4.4 Request-id................................................14
   3.5  Tags .........................................................14
      3.5.1 Delimiter Tags............................................14
      3.5.2 Value Tags................................................15
   3.6  Name-Length ..................................................17
   3.7  (Attribute) Name .............................................18
   3.8  Value Length .................................................18
   3.9  (Attribute) Value ............................................18
   3.10 Data .........................................................20
4. Encoding of Transport Layer .......................................20
   4.1  Printer-uri and job-uri ......................................21
5. IPP URL Scheme ....................................................22
6. IANA Considerations ...............................................24
7. Internationalization Considerations ...............................24
8. Security Considerations ...........................................24
   8.1  Security Conformance Requirements ............................25
      8.1.1 Digest Authentication.....................................25
      8.1.2 Transport Layer Security (TLS)............................26
   8.2  Using IPP with TLS ...........................................26
9. Interoperability with IPP/1.0 Implementations .....................26
   9.1  The "version-number" Parameter ...............................27
   9.2  Security and URL Schemes .....................................27
10. References .......................................................28
11. Author's Address .................................................31
12. Other Participants: ..............................................31
13. Appendix A: Protocol Examples ....................................33
   13.1 Print-Job Request ............................................33
   13.2 Print-Job Response (successful) ..............................34
   13.3 Print-Job Response (failure) .................................35


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   13.4 Print-Job Response (success with attributes ignored) .........36
   13.5 Print-URI Request ............................................38
   13.6 Create-Job Request ...........................................39
   13.7 Get-Jobs Request .............................................40
   13.8 Get-Jobs Response ............................................41
14. Appendix B: Registration of MIME Media Type Information for
"application/ipp".....................................................42
15. Appendix C: Changes from IPP/1.0 .................................44
16. Full Copyright Statement .........................................45









































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1. Introduction

This document contains the rules for encoding IPP operations and
describes two layers: the transport layer and the operation layer.

The transport layer consists of an HTTP/1.1 request or response. RFC
2616 [RFC2616] describes HTTP/1.1. This document specifies the HTTP
headers that an IPP implementation supports.

The operation layer consists of a message body in an HTTP request or
response.  The document "Internet Printing Protocol/1.1: Model and
Semantics" [ipp-mod] defines the semantics of such a message body and
the supported values. This document specifies the encoding of an IPP
operation. The aforementioned document [ipp-mod] is henceforth referred
to as the "IPP model document" or simply "model document."

Note:  the version number of IPP (1.1) and HTTP (1.1) are not linked.
They both just happen to be 1.1.


2. Conformance Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and  "OPTIONAL" in this document are to be
interpreted as described in RFC 2119 [RFC2119].


3. Encoding of  the Operation Layer

The operation layer is the message body part of the HTTP  request or
response and it MUST contain a single IPP operation request or IPP
operation response.  Each request or response consists of a sequence of
values and attribute groups. Attribute groups consist of a sequence of
attributes each of which is a name and value.  Names and values are
ultimately sequences of octets.

The encoding consists of octets as the most primitive type. There are
several types built from octets, but three important types are integers,
character strings and octet strings, on which most other data types are
built. Every character string in this encoding MUST be a sequence of
characters where the characters are associated with some charset and
some natural language. A character string MUST be in "reading order"
with the first character in the value (according to reading order) being
the first character in the encoding. A character string whose associated
charset is US-ASCII whose associated natural language is US English is
henceforth called a US-ASCII-STRING. A character string whose associated
charset and natural language are specified in a request or response as


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described in the model document is henceforth called a LOCALIZED-STRING.
An octet string MUST be in "IPP model document order" with the first
octet in the value (according to the IPP model document order) being the
first octet in the encoding. Every integer in this encoding MUST be
encoded as a signed integer using two's-complement binary encoding with
big-endian format (also known as "network order" and "most significant
byte first"). The number of octets for an integer MUST be 1, 2 or 4,
depending on usage in the protocol. Such one-octet integers, henceforth
called SIGNED-BYTE, are used for the version-number and tag fields. Such
two-byte integers, henceforth called SIGNED-SHORT are used for the
operation-id, status-code and length fields. Four byte integers,
henceforth called SIGNED-INTEGER, are used for value fields and the
request-id.

The following two sections present the encoding of the operation layer
in two ways:

  -  informally through pictures and description
  -  formally through Augmented Backus-Naur Form (ABNF), as specified by
     RFC 2234 [RFC2234]


An operation request or response MUST use the encoding described in
these two sections.


3.1 Picture of the Encoding


3.1.1 Request and Response

An operation request or response is encoded as follows:

  -----------------------------------------------
  |                  version-number             |   2 bytes  - required
  -----------------------------------------------
  |               operation-id (request)        |
  |                      or                     |   2 bytes  - required
  |               status-code (response)        |
  -----------------------------------------------
  |                   request-id                |   4 bytes  - required
  -----------------------------------------------
  |                 attribute-group             |   n bytes - 0 or more
  -----------------------------------------------
  |              end-of-attributes-tag          |   1 byte   - required
  -----------------------------------------------
  |                     data                    |   q bytes  - optional
  -----------------------------------------------


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The first three fields in the above diagram contain the value of
attributes described in section 3.1.1 of the Model document.

The fourth field is the "attribute-group" field, and it occurs 0 or more
times. Each "attribute-group" field represents a single group of
attributes, such as an Operation Attributes group or a Job Attributes
group (see the Model document). The IPP model document specifies the
required attribute groups and their order for each operation request and
response.

The "end-of-attributes-tag" field is always present, even when the
"data" is not present.  The Model document specifies for each operation
request and response whether the "data" field is present or absent.


3.1.2 Attribute Group

Each "attribute-group" field is encoded as follows:

  -----------------------------------------------
  |           begin-attribute-group-tag         |  1 byte
  ----------------------------------------------------------
  |                   attribute                 |  p bytes |- 0 or more
  ----------------------------------------------------------


The "begin-attribute-group-tag" field marks the beginning of an
"attribute-group" field and its value identifies the type of attribute
group, e.g. Operations Attributes group versus a Job Attributes group.
The "begin-attribute-group-tag" field also marks the end of the previous
attribute group except for the "begin-attribute-group-tag" field in the
first "attribute-group" field of a request or response. The "begin-
attribute-group-tag" field acts as an "attribute-group" terminator
because an "attribute-group" field cannot nest inside another
"attribute-group" field.

An "attribute-group" field contains zero or more "attribute" fields.

Note, the values of the "begin-attribute-group-tag" field and the "end-
of-attributes-tag" field are called "delimiter-tags".










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3.1.3 Attribute

An "attribute" field is encoded as follows:

  -----------------------------------------------
  |          attribute-with-one-value           |  q bytes
  ----------------------------------------------------------
  |             additional-value                |  r bytes |- 0 or more
  ----------------------------------------------------------


When an attribute is single valued (e.g. "copies" with value of 10) or
multi-valued with one value (e.g. "sides-supported" with just the value
'one-sided') it is encoded with just an "attribute-with-one-value"
field. When an attribute is multi-valued with n values (e.g. "sides-
supported" with the values 'one-sided' and 'two-sided-long-edge'), it is
encoded with an "attribute-with-one-value" field followed by n-1
"additional-value" fields.


3.1.4 Picture of the Encoding of an Attribute-with-one-value

Each "attribute-with-one-value" field is encoded as follows:

  -----------------------------------------------
  |                   value-tag                 |   1 byte
  -----------------------------------------------
  |               name-length  (value is u)     |   2 bytes
  -----------------------------------------------
  |                     name                    |   u bytes
  -----------------------------------------------
  |              value-length  (value is v)     |   2 bytes
  -----------------------------------------------
  |                     value                   |   v bytes
  -----------------------------------------------

An "attribute-with-one-value" field is encoded with five subfields:

  The "value-tag" field specifies the attribute syntax, e.g. 0x44 for
  the attribute syntax 'keyword'.

  The "name-length" field specifies the length of the "name" field in
  bytes, e.g. u in the above diagram or 15 for the name "sides-
  supported ".

  The "name" field contains the textual name of the attribute, e.g.
  "sides-supported".



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  The "value-length" field specifies the length of the "value" field in
  bytes, e.g. v in the above diagram or 9 for the (keyword) value 'one-
  sided'.

  The "value" field contains the value of the attribute, e.g. the
  textual value 'one-sided'.


3.1.5 Additional-value

Each "additional-value" field is encoded as follows:

  -----------------------------------------------
  |                   value-tag                 |   1 byte
  -----------------------------------------------
  |            name-length  (value is 0x0000)   |   2 bytes
  -----------------------------------------------
  |              value-length (value is w)      |   2 bytes
  -----------------------------------------------
  |                     value                   |   w bytes
  -----------------------------------------------

An "additional-value" is encoded with four subfields:

  The "value-tag" field specifies the attribute syntax, e.g. 0x44 for
  the attribute syntax 'keyword'.

  The "name-length" field has the value of 0 in order to signify that
  it is an "additional-value". The value of the "name-length" field
  distinguishes an "additional-value" field ("name-length" is 0) from
  an "attribute-with-one-value" field ("name-length" is not 0).

  The "value-length" field specifies the length of the "value" field in
  bytes, e.g. w in the above diagram or 19 for the (keyword) value
  'two-sided-long-edge'.

  The "value" field contains the value of the attribute, e.g. the
  textual value 'two-sided-long-edge'.


3.1.6 Alternative Picture of the Encoding of a Request Or a Response

>From the standpoint of a parser that performs an action based on a "tag"
value, the encoding consists of:






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  -----------------------------------------------
  |                  version-number             |   2 bytes  - required
  -----------------------------------------------
  |               operation-id (request)        |
  |                      or                     |   2 bytes  - required
  |               status-code (response)        |
  -----------------------------------------------
  |                   request-id                |   4 bytes  - required
  -----------------------------------------------------------
  |        tag (delimiter-tag or value-tag)     |   1 byte  |
  -----------------------------------------------           |-0 or more
  |           empty or rest of attribute        |   x bytes |
  -----------------------------------------------------------
  |              end-of-attributes-tag          |   1 byte   - required
  -----------------------------------------------
  |                     data                    |   y bytes  - optional
  -----------------------------------------------


The following show what fields the parser would expect after each type
of  "tag":

  -  "begin-attribute-group-tag": expect zero or more "attribute"s
  -  "value-tag": expect the remainder of an "attribute-with-one-value"
     or  an "additional-value".
  -  "end-of-attributes-tag": expect that "attribute"s  are complete and
     there is optional "data"

3.2 Syntax of Encoding

The syntax below is ABNF [RFC2234] except 'strings of literals' MUST be
case sensitive. For example 'a' means lower case  'a' and not upper case
'A'.   In addition, SIGNED-BYTE and SIGNED-SHORT fields are represented
as '%x' values which show their range of values.

  ipp-message = ipp-request / ipp-response
  ipp-request = version-number operation-id request-id
           *attribute-group end-of-attributes-tag data
  ipp-response = version-number status-code request-id
           *attribute-group end-of-attributes-tag  data
  attribute-group = begin-attribute-group-tag attribute



  version-number = major-version-number minor-version-number
  major-version-number = SIGNED-BYTE
  minor-version-number = SIGNED-BYTE



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  operation-id = SIGNED-SHORT    ; mapping from model defined below
  status-code = SIGNED-SHORT  ; mapping from model defined below
  request-id = SIGNED-INTEGER ; whose value is > 0

  attribute = attribute-with-one-value *additional-value

  attribute-with-one-value = value-tag name-length name
      value-length value
  additional-value = value-tag zero-name-length value-length value

  name-length = SIGNED-SHORT    ; number of octets of 'name'
  name = LALPHA *( LALPHA / DIGIT / "-" / "_" / "." )
  value-length = SIGNED-SHORT   ; number of octets of 'value'
  value = OCTET-STRING

  data = OCTET-STRING

  zero-name-length = %x00.00            ; name-length of 0
  value-tag = %x10-FF                  ;see section 3.7.2
  begin-attribute-group-tag = %x00-02 / %04-0F ; see section 3.7.1
  end-of-attributes-tag = %x03                  ; tag of 3
                                ; see section 3.7.1
  SIGNED-BYTE = BYTE
  SIGNED-SHORT = 2BYTE
  SIGNED-INTEGER = 4BYTE
  DIGIT = %x30-39    ;  "0" to "9"
  LALPHA = %x61-7A   ;  "a" to "z"
  BYTE = %x00-FF
  OCTET-STRING = *BYTE

The syntax below defines additional terms that are referenced in this
document. This syntax provides an alternate grouping of the delimiter
tags.

  delimiter-tag = begin-attribute-group-tag  / ; see section 3.7.1
            end-of-attributes-tag
  delimiter-tag = %x00-0F                      ; see section 3.7.1

  begin-attribute-group-tag = %x00 / operation-attributes-tag /
     job-attributes-tag / printer-attributes-tag /
     unsupported-attributes-tag /  %x06-0F
  operation-attributes-tag =  %x01              ; tag of 1
  job-attributes-tag    =  %x02                 ; tag of 2
  printer-attributes-tag =  %x04                ; tag of 4
  unsupported-attributes-tag =  %x05            ; tag of 5





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3.3 Attribute-group

Each "attribute-group" field MUST be encoded with the "begin-attribute-
group-tag" field followed by zero or more "attribute" sub-fields.

The table below maps the model document group name to value of the
"begin-attribute-group-tag" field:


  Model Document Group            "begin-attribute-group-tag" field
                                  values

  Operation Attributes            "operations-attributes-tag"
  Job Template Attributes         "job-attributes-tag"
  Job Object Attributes           "job-attributes-tag"
  Unsupported Attributes          "unsupported-attributes-tag"
  Requested Attributes            "job-attributes-tag"
  (Get-Job-Attributes)
  Requested Attributes            "printer-attributes-tag"
  (Get-Printer-Attributes)
  Document Content                in a special position as described
                                  above


For each operation request and response, the model document prescribes
the required and optional attribute groups, along with their order.
Within each attribute group, the model document prescribes the required
and optional attributes, along with their order.

When the Model document requires an attribute group in a request or
response and the attribute group contains zero attributes, a request or
response SHOULD encode the attribute group with the "begin-attribute-
group-tag" field followed by zero "attribute" fields.  For example, if
the client requests a single unsupported attribute with the Get-Printer-
Attributes operation, the Printer MUST return no "attribute" fields, and
it SHOULD return a "begin-attribute-group-tag" field for the Printer
Attributes Group. The Unsupported Attributes group is not such an
example. According to the model document, the Unsupported Attributes
Group SHOULD be present only if the unsupported attributes group
contains at least one attribute.

A receiver of a request MUST be able to process the following as
equivalent empty attribute groups:

  a) A "begin-attribute-group-tag" field with zero following
  "attribute" fields.

  b) An expected but missing "begin-attribute-group-tag" field.


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When the Model document requires a sequence of an unknown number of
attribute groups, each of the same type, the encoding MUST contain one
"begin-attribute-group-tag" field for each attribute group even when an
"attribute-group" field contains zero "attribute" sub-fields. For
example, for the Get-Jobs operation may return zero attributes for some
jobs and not others. The "begin-attribute-group-tag" field followed by
zero "attribute" fields tells the recipient that there is a job in queue
for which no information is available except that it is in the queue.


3.4 Required Parameters

Some operation elements are called parameters in the model document
[ipp-mod]. They MUST be encoded in a special position and they MUST NOT
appear as operation attributes.  These parameters are described in the
subsections below.


3.4.1 Version-number

The "version-number" field MUST consist of a major and minor version-
number, each of which MUST be represented by a SIGNED-BYTE. The major
version-number MUST be the first byte of the encoding and the minor
version-number MUST be the second byte of the encoding. The protocol
described in this document MUST have a major version-number of 1 (0x01)
and a minor version-number of 1 (0x01).  The ABNF for these two bytes
MUST be %x01.01.


3.4.2 Operation-id

The "operation-id" field MUST contain an operation-id value defined in
the model document. The value MUST be encoded as a SIGNED-SHORT and it
MUST be in the third and fourth bytes of the encoding of an operation
request.


3.4.3 Status-code

The "status-code" field MUST contain a status-code value defined in the
model document. The value MUST be encoded as a SIGNED-SHORT and it MUST
be in the third and fourth bytes of the encoding of an operation
response.

The status-code is an operation attribute in the model document. In the
protocol, the status-code is in a special position, outside of the
operation attributes.



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If an IPP status-code is returned, then the HTTP Status-Code MUST be 200
(successful-ok). With any other HTTP Status-Code value, the HTTP
response MUST NOT contain an IPP message-body, and thus no IPP status-
code is returned.


3.4.4 Request-id

The "request-id" field MUST contain a request-id value as defined in the
model document. The value MUST be encoded as a SIGNED- INTEGER and it
MUST be in the fifth through eighth bytes of the encoding.


3.5 Tags

There are two kinds of tags:

  -  delimiter tags: delimit major sections of the protocol, namely
     attributes and data
  -  value tags: specify the type of each attribute value

3.5.1 Delimiter Tags


The following table specifies the values for the delimiter tags:


   Tag Value (Hex)    Meaning

   0x00               reserved for definition in a future IETF
                      standards track document
   0x01               "operation-attributes-tag"
   0x02               "job-attribute-tag"
   0x03               "end-of-attributes-tag"
   0x04               "printer-attribute-tag"
   0x05               "unsupported-attribute-tag"
   0x06-0x0f          reserved for future delimiters in IETF
                      standards track documents


When a "begin-attribute-group-tag" field occurs in the protocol, it
means that zero or more following attributes up to the next delimiter
tag MUST be attributes belonging to the attribute group specified by the
value of the "begin-attribute-group-tag". For example, if the value of
"begin-attribute-group-tag" is 0x01, the following attributes MUST be
members of the Operations Attributes group.




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The "end-of-attributes-tag" (value 0x03) MUST occur exactly once in an
operation.  It MUST be the last "delimiter-tag". If the operation has a
document-content group, the document data in that group MUST follow the
"end-of-attributes-tag".

The order and presence of "attribute-group" fields (whose beginning is
marked by the "begin-attribute-group-tag" subfield) for each operation
request and each operation response MUST be that defined in the model
document. For further details, see section 3.7 "(Attribute) Name" and 13
"Appendix A: Protocol Examples".

A Printer MUST treat a "delimiter-tag" (values from 0x00 through 0x0F)
differently from a "value-tag" (values from 0x10 through 0xFF) so that
the Printer knows that there is an entire attribute group that it
doesn't understand as opposed to a single value that it doesn't
understand.


3.5.2 Value Tags

The remaining tables show values for the "value-tag" field, which is the
first octet of an attribute. The "value-tag" field specifies the type of
the value of the attribute.

The following table specifies the "out-of-band" values for the "value-
tag" field.


   Tag Value (Hex)  Meaning

   0x10             unsupported
   0x11             reserved for 'default' for definition in a future
                    IETF standards track document
   0x12             unknown
   0x13             no-value
   0x14-0x1F        reserved for "out-of-band" values in future IETF
                    standards track documents.


The following table specifies the integer values for the "value-tag"
field:









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   Tag Value (Hex)   Meaning

   0x20              reserved for definition in a future IETF
                     standards track document
   0x21              integer
   0x22              boolean
   0x23              enum
   0x24-0x2F         reserved for integer types for definition in
                     future IETF standards track documents

NOTE: 0x20 is reserved for "generic integer" if it should ever be
needed.

The following table specifies the octetString values for the "value-tag"
field:


   Tag Value (Hex)   Meaning

   0x30              octetString with an  unspecified format
   0x31              dateTime
   0x32              resolution
   0x33              rangeOfInteger
   0x34              reserved for definition in a future IETF
                     standards track document
   0x35              textWithLanguage
   0x36              nameWithLanguage
   0x37-0x3F         reserved for octetString type definitions in
                     future IETF standards track documents

The following table specifies the character-string values for the
"value-tag" field:

















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   Tag Value (Hex)   Meaning

   0x40              reserved for definition in a future IETF
                     standards track document
   0x41              textWithoutLanguage
   0x42              nameWithoutLanguage
   0x43              reserved for definition in a future IETF
                     standards track document
   0x44              keyword
   0x45              uri
   0x46              uriScheme
   0x47              charset
   0x48              naturalLanguage
   0x49              mimeMediaType
   0x4A-0x5F         reserved for character string type definitions
                     in future IETF standards track documents

NOTE: 0x40 is reserved for "generic character-string" if it should ever
be needed.

NOTE:  an attribute value always has a type, which is explicitly
specified by its tag; one such tag value is "nameWithoutLanguage".   An
attribute's name has an implicit type, which is keyword.

The values 0x60-0xFF are reserved for future type definitions in IETF
standards track documents.

The tag 0x7F is reserved for extending types beyond the 255 values
available with a single byte. A tag value of 0x7F MUST signify that the
first 4 bytes of the value field are interpreted as the tag value.  Note
this future extension doesn't affect parsers that are unaware of this
special tag. The tag is like any other unknown tag, and the value length
specifies the length of a value, which contains a value that the parser
treats atomically.  Values from 0x00 to 0x37777777 are reserved for
definition in future IETF standard track documents.  The values
0x40000000 to 0x7FFFFFFF are reserved for vendor extensions.


3.6 Name-Length

The "name-length" field MUST consist of a SIGNED-SHORT. This field MUST
specify the number of octets in the immediately following "name" field.
The value of this field excludes the two bytes of the "name-length"
field. For example, if the "name" field contains "sides", the value of
this field is 5.




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If a "name-length" field has a value of zero, the following "name" field
MUST be empty, and the following value MUST be treated as an additional
value for the attribute encoded in the nearest preceding "attribute-
with-one-value" field. Within an attribute group, if two or more
attributes have the same name, the attribute group is mal-formed (see
[ipp-mod] section 3.1.3). The zero-length name is the only mechanism for
multi-valued attributes.


3.7 (Attribute) Name

The "name " field MUST contain the name of an attribute. The model
document [ipp-mod] specifies such names.


3.8 Value Length

The "value-length" field MUST consist of a SIGNED-SHORT. This field MUST
specify the number of octets in the immediately following "value" field.
The value of this field excludes the two bytes of the "value-length"
field. For example, if the "value" field contains the keyword (text)
value 'one-sided', the value of this field is 9.

For any of the types represented by binary signed integers, the sender
MUST encode the value in exactly four octets.

For any of the types represented by character-strings, the sender MUST
encode the value with all the characters of the string and without any
padding characters.

For "out-of-band" "value-tag"s defined in this document, such as
"unsupported", the "value-length" MUST be 0 and the "value" empty; the
"value" has no meaning when the "value-tag" has one of these "out-of-
band" values. For future "out-of-band" "value-tag"s, the same rule holds
unless the definition explicitly states that the "value-length" MAY be
non-zero and the "value" non-empty


3.9 (Attribute) Value

The syntax types (specified by the "value-tag" field) and most of the
details of the representation of attribute values are defined in the IPP
model document. The table below augments the information in the model
document, and defines the syntax types from the model document in terms
of the 5 basic types defined in section 3  "Encoding of  the Operation
Layer". The 5 types are US-ASCII-STRING, LOCALIZED-STRING, SIGNED-
INTEGER, SIGNED-SHORT, SIGNED-BYTE, and OCTET-STRING.



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Syntax of Attribute   Encoding
Value

textWithoutLanguage,  LOCALIZED-STRING.
nameWithoutLanguage

textWithLanguage      OCTET_STRING consisting of 4 fields:
                        a. a SIGNED-SHORT which is the number of
                           octets in the following field
                        b. a value of type natural-language,
                        c. a SIGNED-SHORT which is the number of
                           octets in the following field,
                        d. a value of type textWithoutLanguage.
                      The length of a textWithLanguage value MUST be 4
                      + the value of field a + the value of field c.

nameWithLanguage      OCTET_STRING consisting of 4 fields:
                        a. a SIGNED-SHORT which is the number of
                           octets in the following field
                        b. a value of type natural-language,
                        c. a SIGNED-SHORT which is the number of
                           octets in the following field
                        d. a value of type nameWithoutLanguage.
                      The length of a nameWithLanguage value MUST be 4
                      + the value of field a + the value of field c.

charset,              US-ASCII-STRING.
naturalLanguage,
mimeMediaType,
keyword, uri, and
uriScheme

boolean               SIGNED-BYTE  where 0x00 is 'false' and 0x01 is
                      'true'.

integer and enum      a SIGNED-INTEGER.

dateTime              OCTET-STRING consisting of eleven octets whose
                      contents are defined by "DateAndTime" in RFC
                      1903 [RFC1903].

resolution            OCTET_STRING consisting of nine octets of  2
                      SIGNED-INTEGERs followed by a SIGNED-BYTE. The
                      first SIGNED-INTEGER contains the value of cross
                      feed direction resolution. The second SIGNED-
                      INTEGER contains the value of feed direction
                      resolution. The SIGNED-BYTE contains the units


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Syntax of Attribute   Encoding
Value

                      value.

rangeOfInteger        Eight octets consisting of 2 SIGNED-INTEGERs.
                      The first SIGNED-INTEGER contains the lower
                      bound and the second SIGNED-INTEGER contains the
                      upper  bound.

1setOf  X             Encoding according to the rules for an attribute
                      with more than 1 value.  Each value X is encoded
                      according to the rules for encoding its type.

octetString           OCTET-STRING


The attribute syntax type of the value determines its encoding and the
value of its "value-tag".


3.10 Data

The "data" field MUST include any data required by the operation


4. Encoding of Transport Layer

HTTP/1.1 [RFC2616] is the transport layer for this protocol.

The operation layer has been designed with the assumption that the
transport layer contains the following information:

  -  the URI of the target job or printer operation
  -  the total length of the data in the operation layer, either as a
     single length or as a sequence of chunks each with a length.


It is REQUIRED that a printer implementation support HTTP over the IANA
assigned Well Known Port 631 (the IPP default port), though a printer
implementation may support HTTP over some other port as well.

Each HTTP operation MUST use the POST method where the request-URI is
the object target of the operation, and where the "Content-Type" of the
message-body in each request and response MUST be "application/ipp". The
message-body MUST contain the operation layer and MUST have the syntax
described in section 3.2 "Syntax of Encoding". A client implementation


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MUST adhere to the rules for a client described for HTTP1.1 [RFC2616] .
A printer (server) implementation MUST adhere the rules for an origin
server described for HTTP1.1 [RFC2616].

An IPP server sends a response for each request that it receives.  If an
IPP server detects an error, it MAY send a response before it has read
the entire request.  If the HTTP layer of the IPP server completes
processing the HTTP headers successfully, it MAY send an intermediate
response, such as "100 Continue", with no IPP data before sending the
IPP response.  A client MUST expect such a variety of responses from an
IPP server. For further information on HTTP/1.1, consult the HTTP
documents [RFC2616].

An HTTP server MUST support chunking for IPP requests, and an IPP client
MUST support chunking for IPP responses according to  HTTP/1.1[RFC2616].
Note: this rule causes a conflict with non-compliant implementations of
HTTP/1.1 that don't support chunking for POST methods, and this rule may
cause a conflict with non-compliant implementations of HTTP/1.1 that
don't support chunking for CGI scripts


4.1 Printer-uri and job-uri

All Printer and Job objects are identified by a Uniform Resource
Identifier (URI) [RFC2396] so that they can be persistently and
unambiguously referenced.  The notion of a URI is a useful concept,
however, until the notion of URI is more stable (i.e.,  defined more
completely and deployed more widely), it is expected that the URIs used
for IPP objects will actually be URLs [RFC1738]  [RFC1808].  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.

Some operation elements are encoded twice, once as the request-URI on
the HTTP Request-Line and a second time as a REQUIRED operation
attribute in the application/ipp entity.  These attributes are the
target URI for the operation and are called printer-uri and job-uri.
Note: The target URI is included twice in an operation referencing the
same IPP object, but the two URIs NEED NOT be literally identical. One
can be a relative URI and the other can be an absolute URI.  HTTP/1.1
allows clients to generate and send a relative URI rather than an
absolute URI.  A relative URI identifies a resource with the scope of
the HTTP server, but does not include scheme, host or port.  The
following statements characterize how URLs should be used in the mapping
of IPP onto HTTP/1.1:

  1. Although potentially redundant, a client MUST supply the target of
     the operation both as an operation attribute and as a URI at the


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     HTTP layer.  The rationale for this decision is to maintain a
     consistent set of rules for mapping application/ipp to possibly
     many communication layers, even where URLs are not used as the
     addressing mechanism in the transport layer.
  2. Even though these two URLs might not be literally identical (one
     being relative and the other being absolute), they MUST both
     reference the same IPP object. However, a Printer NEED NOT verify
     that the two URLs reference the same IPP object, and NEED NOT take
     any action if it determines the two URLs to be different.
  3. The URI in the HTTP layer is either relative or absolute and is
     used by the HTTP server to route the HTTP request to the correct
     resource relative to that HTTP server.  The HTTP server need not
     be aware of the URI within the operation request.
  4. Once the HTTP server resource begins to process the HTTP request,
     it might get the reference to the appropriate IPP Printer object
     from either the HTTP URI (using to the context of the HTTP server
     for relative URLs) or from the URI within the operation request;
     the choice is up to the implementation.
  5. HTTP URIs can be relative or absolute, but the target URI in the
     operation MUST be an absolute URI.

5. IPP URL Scheme

The IPP/1.1 document defines a new scheme 'ipp' as the value of a URL
that identifies either an IPP printer object or an IPP job object. The
IPP attributes using the 'ipp' scheme are specified below.  Because the
HTTP layer does not support the 'ipp' scheme, a client MUST map 'ipp'
URLs to 'http' URLs, and then follows the HTTP [RFC2616][RFC2617] rules
for constructing a Request-Line and HTTP headers.  The mapping is simple
because the 'ipp' scheme implies all of the same protocol semantics as
that of the 'http' scheme [RFC2616], except that it represents a print
service and the implicit (default) port number that clients use to
connect to a server is port 631.

In the remainder of this section the term 'ipp-URL' means a URL whose
scheme is 'ipp' and whose implicit (default) port is 631. The term
'http-URL' means a URL whose scheme is 'http', and the term 'https-URL'
means a URL whose scheme is 'https',

A client and an IPP object (i.e. the server) MUST support the ipp-URL
value in the following IPP attributes.
    job attributes:
        job-uri
        job-printer-uri
    printer attributes:
        printer-uri-supported
    operation attributes:
        job-uri


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        printer-uri
Each of the above attributes identifies a printer or job object. The
ipp-URL is intended as the value of the attributes in this list, and for
no other attributes. All of these attributes have a syntax type of
'uri', but there are attributes with a syntax type of 'uri' that do not
use the 'ipp' scheme, e.g. 'job-more-info'.

If a printer registers its URL with a directory service, the printer
MUST register an ipp-URL.

User interfaces are beyond the scope of this document. But if software
exposes the ipp-URL values of any of the above five attributes to a
human user, it is REQUIRED that the human see the ipp-URL as is.

When a client sends a request, it MUST convert a target ipp-URL to a
target http-URL for the HTTP layer according to the following rules:
  1. change the 'ipp' scheme to 'http'
  2. add an explicit port 631 if the URL does not contain an explicit
     port. Note: port 631 is the IANA assigned Well Known Port for the
     'ipp' scheme.

The client  MUST use the target http-URL in both the HTTP Request-Line
and HTTP headers, as specified by HTTP[RFC2616][RFC2617] . However, the
client MUST use the target ipp-URL for the value of the "printer-uri" or
"job-uri" operation attribute within the application/ipp body of the
request. The server MUST use the ipp-URL for the value of the "printer-
uri", "job-uri" or "printer-uri-supported" attributes within the
application/ipp body of the response.

For example, when an IPP client sends a request directly (i.e. no proxy)
to an ipp-URL   "ipp://myhost.com/myprinter/myqueue", it opens a TCP
connection to port 631 (the ipp implicit port) on the host "myhost.com"
and sends the following data:

POST /myprinter/myqueue HTTP/1.1
Host: myhost.com:631
Content-type: application/ipp
Transfer-Encoding: chunked
...
"printer-uri" "ipp://myhost.com/myprinter/myqueue"
          (encoded in application/ipp message body)
...

As another example, when an IPP client sends the same request as above
via a proxy  "myproxy.com", it opens a TCP connection to the proxy port
8080 on the proxy host "myproxy.com" and sends the following data:

POST http://myhost.com:631/myprinter/myqueue   HTTP/1.1


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Host: myhost.com:631
Content-type: application/ipp
Transfer-Encoding: chunked
...
"printer-uri" "ipp://myhost.com/myprinter/myqueue"
          (encoded in application/ipp message body)
...

The proxy then connects to the IPP origin server with headers that are
the same as the "no-proxy" example above.

6. IANA Considerations

This section describes the procedures for allocating encoding for the
following IETF standards track extensions and vendor extensions to the
IPP/1.1 Encoding and Transport document:

  1. attribute syntaxes - see [ipp-mod] section 6.3
  2. attribute groups - see [ipp-mod] section 6.5
  3. out-of-band attribute values - see [ipp-mod] section 6.7


These extensions follow the "type2" registration procedures defined in
[ipp-mod] section 6.  Extensions registered for use with IPP/1.1 are
OPTIONAL for client and IPP object conformance to the IPP/1.1 Encoding
and Transport document.

These extension procedures are aligned with the guidelines as set forth
by the IESG [IANA-CON].  The [ipp-mod] Section 11 describes how to
propose new registrations for consideration.  IANA will reject
registration proposals that leave out required information or do not
follow the appropriate format described in [ipp-mod] Section 11.  The
IPP/1.1 Encoding and Transport document may also be extended by an
appropriate RFC that specifies any of the above extensions.


7. Internationalization Considerations

See the section on "Internationalization Considerations" in the document
"Internet Printing Protocol/1.1: Model and Semantics" [ipp-mod] for
information on internationalization. This document adds no additional
issues.


8. Security Considerations

The IPP Model and Semantics document [ipp-mod] discusses high level
security requirements (Client Authentication, Server Authentication and


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Operation Privacy). Client Authentication is the mechanism by which the
client proves its identity to the server in a secure manner. Server
Authentication is the mechanism by which the server proves its identity
to the client in a secure manner. Operation Privacy is defined as a
mechanism for protecting operations from eavesdropping.


8.1 Security Conformance Requirements

This section defines the security requirements for IPP clients and IPP
objects.


8.1.1 Digest Authentication

IPP clients MUST support:

  Digest Authentication [RFC2617].

     MD5 and MD5-sess MUST be implemented and supported.

     The Message Integrity feature NEED NOT be used.



IPP Printers SHOULD support:

  Digest Authentication [RFC2617].

     MD5 and MD5-sess MUST be implemented and supported.

     The Message Integrity feature NEED NOT be used.

The reasons that IPP Printers SHOULD (rather than MUST) support Digest
Authentication are:

1.While Client Authentication is important, there is a certain class of
  printer devices where it does not make sense.  Specifically, a low-
  end device with limited ROM space and low paper throughput may not
  need Client Authentication.  This class of device typically requires
  firmware designers to make trade-offs between protocols and
  functionality to arrive at the lowest-cost solution possible.
  Factored into the designer's decisions is not just the size of the
  code, but also the testing, maintenance, usefulness, and time-to-
  market impact for each feature delivered to the customer.  Forcing
  such low-end devices to provide security in order to claim IPP/1.1
  conformance would not make business sense and could potentially stall
  the adoption of the standard.


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2.Print devices that have high-volume throughput and have available ROM
  space have a compelling argument to provide support for Client
  Authentication that safeguards the device from unauthorized access.
  These devices are prone to a high loss of consumables and paper if
  unauthorized access should occur.


8.1.2 Transport Layer Security (TLS)

IPP Printers SHOULD support Transport Layer Security (TLS) [RFC2246] for
Server Authentication and Operation Privacy. IPP Printers MAY also
support TLS for Client Authentication.  If an IPP Printer supports TLS,
it MUST support the TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite as
mandated by RFC 2246 [RFC2246].  All other cipher suites are OPTIONAL.
An IPP Printer MAY support Basic Authentication (described in HTTP/1.1
[RFC2617])  for Client Authentication if the channel is secure. TLS with
the above mandated cipher suite can provide such a secure channel.

If a IPP client supports TLS, it MUST support the
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite as mandated by RFC 2246
[RFC2246].  All other cipher suites are OPTIONAL.

The IPP Model and Semantics document defines two printer attributes
("uri-authentication-supported" and "uri-security-supported") that the
client can use to discover the security policy of a printer. That
document also outlines IPP-specific security considerations and should
be the primary reference for security implications with regard to the
IPP protocol itself.  For backward compatibility with IPP version 1.0,
IPP clients and printers may also support SSL3 [ssl]. This is in
addition to the security required in this document.


8.2 Using IPP with TLS

IPP/1.1 uses the "Upgrading to TLS Within HTTP/1.1" mechanism [RFC2817].
An initial IPP request never uses TLS.  The client requests a secure TLS
connection by using the HTTP "Upgrade" header, while the server agrees
in the HTTP response.  The switch to TLS occurs either because the
server grants the client's request to upgrade to TLS, or a server asks
to switch to TLS in its response.  Secure communication begins with a
server's response to switch to TLS.


9. Interoperability with IPP/1.0 Implementations

It is beyond the scope of this specification to mandate conformance with
previous versions.  IPP/1.1 was deliberately designed, however, to make


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supporting previous versions easy.  It is worth noting that, at the time
of composing this specification (1999), we would expect IPP/1.1 Printer
implementations to:

     understand any valid request in the format of IPP/1.0, or 1.1;

     respond appropriately with a response containing the same "version-
     number" parameter value used by the client in the request.

And we would expect IPP/1.1 clients to:

     understand any valid response in the format of IPP/1.0, or 1.1.


9.1 The "version-number" Parameter

The following are rules regarding the "version-number" parameter (see
section 3.3):

   1. Clients MUST send requests containing a "version-number" parameter
      with a '1.1' value and SHOULD try supplying alternate version
      numbers if they receive a 'server-error-version-not-supported'
      error return in a response.

   2. IPP objects MUST accept requests containing a "version-number"
      parameter with a '1.1' value (or reject the request for reasons
      other than 'server-error-version-not-supported').

   3. It is recommended that IPP objects accept any request with the
      major version '1' (or reject the request for reasons other than
      'server-error-version-not-supported').  See [ipp-mod] "versions"
      sub-section.

   4. In any case, security MUST NOT be compromised when a client
      supplies a lower "version-number" parameter in a request.  For
      example, if an IPP/1.1 conforming Printer object accepts version
      '1.0' requests and is configured to enforce Digest Authentication,
      it MUST do the same for a version '1.0' request.


9.2 Security and URL Schemes

The following are rules regarding security, the "version-number"
parameter, and the URL scheme supplied in target attributes and
responses:

   1. When a client supplies a request, the "printer-uri" or "job-uri"
      target operation attribute MUST have the same scheme as that


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      indicated in one of the values of the "printer-uri-supported"
      Printer attribute.

   2. When the server returns the "job-printer-uri" or "job-uri" Job
      Description attributes, it SHOULD return the same scheme ('ipp',
      'https', 'http', etc.) that the client supplied in the "printer-
      uri" or "job-uri" target operation attributes in the Get-Job-
      Attributes or Get-Jobs request, rather than the scheme used when
      the job was created.  However, when a client requests job
      attributes using the Get-Job-Attributes or Get-Jobs operations,
      the jobs and job attributes that the server returns depends on:
      (1) the security in effect when the job was created, (2) the
      security in effect in the query request, and (3) the security
      policy in force.

   3. It is recommended that if a server registers a non-secure ipp-URL
      with a directory service (see [IPP-MOD] "Generic Directory Schema"
      Appendix), then it also register an http-URL for interoperability
      with IPP/1.0 clients (see section 9).

   4. In any case, security MUST NOT be compromised when a client
      supplies an 'http' or other non-secure URL scheme in the target
      "printer-uri" and "job-uri" operation attributes in a request.


10. References

[dpa] ISO/IEC 10175 Document Printing Application (DPA), June 1996.

[iana]IANA Registry of Coded Character Sets: ftp://ftp.isi.edu/in-
      notes/iana/assignments/character-sets.

[ipp-iig] Hastings, Tom, et al., "Internet Printing Protocol/1.1:
      Implementer's Guide", draft-ietf-ipp-implementers-guide-v11-
      00.txt, work in progress, September 27, 1999.

[ipp-mod] R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
      "Internet Printing Protocol/1.1: Model and Semantics", <draft-
      ietf-ipp-model-v11-07.txt>, May 22, 2000.

[ipp-pro] Herriot, R., Butler, S., Moore, P., Turner, R., "Internet
      Printing Protocol/1.1: Encoding and Transport", draft-ietf-ipp-
      protocol-v11-06.txt, May 30, 2000.

[RFC822]  Crocker, D., "Standard for the Format of ARPA Internet Text
      Messages", RFC 822, August 1982.




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[RFC1123] Braden, S., "Requirements for Internet Hosts - Application
      and Support", RFC 1123, October, 1989.

[RFC1179] McLaughlin, L. III, (editor), "Line Printer Daemon Protocol"
      RFC 1179, August 1990.

[RFC1543] Postel, J., "Instructions to RFC Authors", RFC 1543, October
      1993.

[RFC1738] Berners-Lee, T., Masinter, L., McCahill, M. , "Uniform
      Resource Locators (URL)", RFC 1738, December, 1994.

[RFC1759] Smith, R., Wright, F., Hastings, T., Zilles, S., and
      Gyllenskog, J., "Printer MIB", RFC 1759, March 1995.

[RFC1766] H. Alvestrand, " Tags for the Identification of Languages",
      RFC 1766, March 1995.

[RFC1808] R. Fielding, "Relative Uniform Resource Locators", RFC1808,
      June 1995.

[RFC1903] J. Case, et al. "Textual Conventions for Version 2 of the
      Simple Network Management Protocol (SNMPv2)", RFC 1903, January
      1996.

[RFC2046] N. Freed & N. Borenstein, Multipurpose Internet Mail
      Extensions (MIME) Part Two: Media Types. November 1996, RFC 2046.

[RFC2048] N. Freed, J. Klensin & J. Postel.  Multipurpose Internet Mail
      Extension (MIME) Part Four: Registration Procedures. November
      1996 (Also BCP0013), RFC 2048.

[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
      Requirement Levels", RFC 2119 , March 1997.

[RFC2184] N. Freed, K. Moore, "MIME Parameter Value and Encoded Word
      Extensions: Character Sets, Languages, and Continuations", RFC
      2184, August 1997.

[RFC2234] D. Crocker et al., "Augmented BNF for Syntax Specifications:
      ABNF", RFC 2234. November 1997.

[RFC2246] T. Dierks et al., "The TLS Protocol", RFC 2246. January 1999.

[RFC2396] Berners-Lee, T., Fielding, R., Masinter, L., "Uniform
      Resource Identifiers (URI): Generic Syntax", RFC 2396, August
      1998.



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[RFC2565] Herriot, R., Butler, S., Moore, P., Turner, R., "Internet
      Printing Protocol/1.0: Encoding and Transport", RFC 2565, April
      1999.

[RFC2566] R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
      "Internet Printing Protocol/1.0: Model and Semantics", RFC 2566,
      April, 1999.

[RFC2567] Wright, D., "Design Goals for an Internet Printing Protocol",
      RFC2567, April 1999.

[RFC2568] Zilles, S., "Rationale for the Structure and Model and
      Protocol for the Internet Printing Protocol", RC 2568, April
      1999.

[RFC2569] Herriot, R., Hastings, T., Jacobs, N., Martin, J., "Mapping
      between LPD and IPP Protocols RFC 2569, April 1999.

[RFC2616]
      R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P.
      Leach, T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1",
      RFC 2616, June 1999.

[RFC2617]
      J. Franks, P. Hallam-Baker, J. Hostetler, S. Lawrence, P. Leach,
      A. Luotonen, L. Stewart, "HTTP Authentication: Basic and Digest
      Access Authentication", RFC 2617, June 1999.

[RFC2817] R. Khare, S. Lawrence, "Upgrading to TLS Within HTTP/1.1",
      RFC 2817, May 2000.

[SSL]
      Netscape, The SSL Protocol, Version 3, (Text version 3.02),
      November 1996.
















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11. Author's Address

Robert Herriot (editor)             Paul Moore
Xerox Corporation                   Peerless Systems Networking
3400 Hillview Ave., Bldg #1         10900 NE 8th St #900
Palo Alto, CA 94304                 Bellevue, WA 98004

Phone: 650-813-7696                 Phone: 425-462-5852
Fax:  650-813-6860
Email:                              Email: pmoore@peerless.com
robert.herriot@pahv.xerox.com

Sylvan Butler                       Randy Turner
Hewlett-Packard                     2Wire, Inc.
11311 Chinden Blvd.                 694 Tasman Dr.
Boise, ID 83714                     Milpitas, CA 95035

Phone: 208-396-6000                 Phone: 408-546-1273
Fax: 208-396-3457
Email: sbutler@boi.hp.com

                                    John Wenn
                                    Xerox Corporation
                                    737 Hawaii St
                                    El Segundo, CA  90245

IPP Mailing List:  ipp@pwg.org      Phone: 310-333-5764
IPP Mailing List Subscription:      Fax: 310-333-5514
ipp-request@pwg.org
IPP Web Page:                       Email: jwenn@cp10.es.xerox.com
http://www.pwg.org/ipp/


12. Other Participants:

Chuck Adams - Tektronix             Shivaun Albright - HP
Stefan Andersson - Axis             Jeff Barnett - IBM
Ron Bergman - Hitachi Koki Imaging  Dennis Carney - IBM
Systems
Keith Carter - IBM                  Angelo Caruso - Xerox
Rajesh Chawla - TR Computing        Nancy Chen - Okidata
Solutions
Josh Cohen - Microsoft              Jeff Copeland - QMS
Andy Davidson - Tektronix           Roger deBry - IBM
Maulik Desai - Auco                 Mabry Dozier - QMS
Lee Farrell - Canon Information     Satoshi Fujitami - Ricoh
Systems
Steve Gebert - IBM                  Sue Gleeson - Digital


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Charles Gordon - Osicom             Brian Grimshaw - Apple
Jerry Hadsell - IBM                 Richard Hart - Digital
Tom Hastings - Xerox                Henrik Holst - I-data
Stephen Holmstead                   Zhi-Hong Huang - Zenographics
Scott Isaacson - Novell             Babek Jahromi - Microsoft
Swen Johnson - Xerox                David Kellerman - Northlake
                                    Software
Robert Kline - TrueSpectra          Charles Kong - Panasonic
Carl Kugler - IBM                   Dave Kuntz - Hewlett-Packard
Takami Kurono - Brother             Rick Landau - Digital
Scott Lawrence - Agranot Systems    Greg LeClair - Epson
Dwight Lewis - Lexmark              Harry Lewis - IBM
Tony Liao - Vivid Image             Roy Lomicka - Digital
Pete Loya - HP                      Ray Lutz - Cognisys
Mike MacKay - Novell, Inc.          David Manchala - Xerox
Carl-Uno Manros - Xerox             Jay Martin - Underscore
Stan McConnell - Xerox              Larry Masinter - Xerox
Sandra Matts - Hewlett Packard      Peter Michalek - Shinesoft
Ira McDonald - High North Inc.      Mike Moldovan - G3 Nova
Tetsuya Morita - Ricoh              Yuichi Niwa - Ricoh
Pat Nogay - IBM                     Ron Norton - Printronics
Hugo Parra, Novell                  Bob Pentecost - Hewlett-Packard
Patrick Powell - Astart             Jeff Rackowitz - Intermec
Technologies
Eric Random - Peerless              Rob Rhoads - Intel
Xavier Riley - Xerox                Gary Roberts - Ricoh
David Roach - Unisys                Stuart Rowley - Kyocera
Yuji Sasaki - Japan Computer        Richard Schneider - Epson
Industry
Kris Schoff - HP                    Katsuaki Sekiguchi - Canon
                                    Information Systems
Bob Setterbo - Adobe                Gail Songer - Peerless
Hideki Tanaka - Cannon Information  Devon Taylor - Novell, Inc.
Systems
Mike Timperman - Lexmark            Atsushi Uchino - Epson
Shigeru Ueda - Canon                Bob Von Andel - Allegro Software
William Wagner - NetSilicon/DPI     Jim Walker - DAZEL
Chris Wellens - Interworking Labs   Trevor Wells - Hewlett Packard
Craig Whittle - Sharp Labs          Rob Whittle - Novell, Inc.
Jasper Wong - Xionics               Don Wright - Lexmark
Michael Wu - Heidelberg Digital     Rick Yardumian - Xerox
Michael Yeung - Canon Information   Lloyd Young - Lexmark
Systems
Atsushi Yuki - Kyocera              Peter Zehler - Xerox
William Zhang- Canon Information    Frank Zhao - Panasonic
Systems
Steve Zilles - Adobe                Rob Zirnstein - Canon Information
                                    Systems


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13. Appendix A: Protocol Examples


13.1 Print-Job Request

The following is an example of a Print-Job request with job-name,
copies, and sides specified. The "ipp-attribute-fidelity" attribute is
set to 'true' so that the print request will fail if the "copies" or the
"sides" attribute are not supported or their values are not supported.


Octets          Symbolic Value                Protocol field

0x0101          1.1                           version-number
0x0002          Print-Job                     operation-id
0x00000001      1                             request-id
0x01            start operation-attributes    operation-attributes-tag
0x47            charset type                  value-tag
0x0012                                        name-length
attributes-     attributes-charset            name
charset
0x0008                                        value-length
us-ascii        US-ASCII                      value
0x48            natural-language type         value-tag
0x001B                                        name-length
attributes-                                   name
natural-        attributes-natural-language
language
0x0005                                        value-length
en-us           en-US                         value
0x45            uri type                      value-tag
0x000B                                        name-length
printer-uri     printer-uri                   name
0x0015                                        value-length
ipp://forest/p  printer pinetree              value
inetree
0x42            nameWithoutLanguage type      value-tag
0x0008                                        name-length
job-name        job-name                      name
0x0006                                        value-length
foobar          foobar                        value
0x22            boolean type                  value-tag
0x0016                                        name-length
ipp-attribute-  ipp-attribute-fidelity        name
fidelity
0x0001                                        value-length
0x01            true                          value


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Octets          Symbolic Value                Protocol field

0x02            start job-attributes          job-attributes-tag
0x21            integer type                  value-tag
0x0006                                        name-length
copies          copies                        name
0x0004                                        value-length
0x00000014      20                            value
0x44            keyword type                  value-tag
0x0005                                        name-length
sides           sides                         name
0x0013                                        value-length
two-sided-      two-sided-long-edge           value
long-edge
0x03            end-of-attributes             end-of-attributes-tag
%!PS...         <PostScript>                  data

13.2 Print-Job Response (successful)

Here is an example of a successful Print-Job response to the previous
Print-Job request.  The printer supported the "copies" and "sides"
attributes and their supplied values.  The status code returned is
'successful-ok'.


Octets            Symbolic Value              Protocol field

0x0101            1.1                         version-number
0x0000            successful-ok               status-code
0x00000001        1                           request-id
0x01              start operation-attributes  operation-attributes-tag
0x47              charset type                value-tag
0x0012                                        name-length
attributes-       attributes-charset          name
charset
0x0008                                        value-length
us-ascii          US-ASCII                    value
0x48              natural-language type       value-tag
0x001B                                        name-length
attributes-       attributes-natural-         name
natural-language  language
0x0005                                        value-length
en-us             en-US                       value
0x41              textWithoutLanguage type    value-tag
0x000E                                        name-length
status-message    status-message              name
0x000D                                        value-length


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Octets            Symbolic Value              Protocol field

successful-ok     successful-ok               value
0x02              start job-attributes        job-attributes-tag
0x21              integer                     value-tag
0x0006                                        name-length
job-id            job-id                      name
0x0004                                        value-length
147               147                         value
0x45              uri type                    value-tag
0x0007                                        name-length
job-uri           job-uri                     name
0x0019                                        value-length
ipp://forest/pin  job 123 on pinetree         value
etree/123
0x23              enum type                   value-tag
0x0009                                        name-length
job-state         job-state                   name
0x0004                                        value-length
0x0003            pending                     value
0x03              end-of-attributes           end-of-attributes-tag


13.3 Print-Job Response (failure)

Here is an example of an unsuccessful Print-Job response to the previous
Print-Job request. It fails because, in this case, the printer does not
support the "sides" attribute and because the value '20' for the
"copies" attribute is not supported. Therefore, no job is created, and
neither a "job-id" nor a "job-uri" operation attribute is returned. The
error code returned is 'client-error-attributes-or-values-not-supported'
(0x040B).


Octets        Symbolic Value                Protocol field

0x0101        1.1                           version-number
0x040B        client-error-attributes-or-   status-code
              values-not-supported
0x00000001    1                             request-id
0x01          start operation-attributes    operation-attribute tag
0x47          charset type                  value-tag
0x0012                                      name-length
attributes-   attributes-charset            name
charset
0x0008                                      value-length
us-ascii      US-ASCII                      value


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Octets        Symbolic Value                Protocol field

0x48          natural-language type         value-tag
0x001B                                      name-length
attributes-   attributes-natural-language   name
natural-
language
0x0005                                      value-length
en-us         en-US                         value
0x41          textWithoutLanguage type      value-tag
0x000E                                      name-length
status-       status-message                name
message
0x002F                                      value-length
client-error-                               value
attributes-   values-not-supported
or-values-    client-error-attributes-or-
not-supported
0x05          start unsupported-attributes  unsupported-attributes tag
0x21          integer type                  value-tag
0x0006                                      name-length
copies        copies                        name
0x0004                                      value-length
0x00000014    20                            value
0x10          unsupported  (type)           value-tag
0x0005                                      name-length
sides         sides                         name
0x0000                                      value-length
0x03          end-of-attributes             end-of-attributes-tag

13.4 Print-Job Response (success with attributes ignored)

Here is an example of a successful Print-Job response to a Print-Job
request like the previous Print-Job request, except that the value of
'ipp-attribute-fidelity' is false. The print request succeeds, even
though, in this case, the printer supports neither the "sides" attribute
nor the value '20' for the "copies" attribute. Therefore, a job is
created, and both a "job-id" and a "job-uri" operation attribute are
returned. The unsupported attributes are also returned in an Unsupported
Attributes Group. The error code returned is 'successful-ok-ignored-or-
substituted-attributes' (0x0001).


Octets            Symbolic Value              Protocol field

0x0101            1.1                         version-number
0x0001            successful-ok-ignored-or-   status-code


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Octets            Symbolic Value              Protocol field

                  substituted-attributes
0x00000001        1                           request-id
0x01              start operation-attributes  operation-attributes-tag
0x47              charset type                value-tag
0x0012                                        name-length
attributes-       attributes-charset          name
charset
0x0008                                        value-length
us-ascii          US-ASCII                    value
0x48              natural-language type       value-tag
0x001B                                        name-length
attributes-       attributes-natural-         name
natural-language  language
0x0005                                        value-length
en-us             en-US                       value
0x41              textWithoutLanguage type    value-tag
0x000E                                        name-length
status-message    status-message              name
0x002F                                        value-length
successful-ok-    successful-ok-ignored-or-   value
ignored-or-       substituted-attributes
substituted-
attributes
0x05              start unsupported-          unsupported-attributes
                  attributes                  tag
0x21              integer type                value-tag
0x0006                                        name-length
copies            copies                      name
0x0004                                        value-length
0x00000014        20                          value
0x10              unsupported  (type)         value-tag
0x0005                                        name-length
sides             sides                       name
0x0000                                        value-length
0x02              start job-attributes        job-attributes-tag
0x21              integer                     value-tag
0x0006                                        name-length
job-id            job-id                      name
0x0004                                        value-length
147               147                         value
0x45              uri type                    value-tag
0x0007                                        name-length
job-uri           job-uri                     name
0x0019                                        value-length
ipp://forest/pin  job 123 on pinetree         value


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Octets            Symbolic Value              Protocol field

etree/123
0x23              enum  type                  value-tag
0x0009                                        name-length
job-state         job-state                   name
0x0004                                        value-length
0x0003            pending                     value
0x03              end-of-attributes           end-of-attributes-tag


13.5 Print-URI Request

The following is an example of Print-URI request with copies and job-
name parameters:


Octets         Symbolic Value               Protocol field

0x0101         1.1                          version-number
0x0003         Print-URI                    operation-id
0x00000001     1                            request-id
0x01           start operation-attributes   operation-attributes-tag
0x47           charset type                 value-tag
0x0012                                      name-length
attributes-    attributes-charset           name
charset
0x0008                                      value-length
us-ascii       US-ASCII                     value
0x48           natural-language type        value-tag
0x001B                                      name-length
attributes-    attributes-natural-language  name
natural-
language
0x0005                                      value-length
en-us          en-US                        value
0x45           uri type                     value-tag
0x000B                                      name-length
printer-uri    printer-uri                  name
0x0015                                      value-length
ipp://forest/  printer pinetree             value
pinetree
0x45           uri type                     value-tag
0x000C                                      name-length
document-uri   document-uri                 name
0x0011                                      value-length
ftp://foo.com  ftp://foo.com/foo            value


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Octets         Symbolic Value               Protocol field

/foo
0x42           nameWithoutLanguage type     value-tag
0x0008                                      name-length
job-name       job-name                     name
0x0006                                      value-length
foobar         foobar                       value
0x02           start job-attributes         job-attributes-tag
0x21           integer type                 value-tag
0x0006                                      name-length
copies         copies                       name
0x0004                                      value-length
0x00000001     1                            value
0x03           end-of-attributes            end-of-attributes-tag


13.6 Create-Job Request

The following is an example of Create-Job request with no parameters and
no attributes:


Octets         Symbolic Value               Protocol field

0x0101         1.1                          version-number
0x0005         Create-Job                   operation-id
0x00000001     1                            request-id
0x01           start operation-attributes   operation-attributes-tag
0x47           charset type                 value-tag
0x0012                                      name-length
attributes-    attributes-charset           name
charset
0x0008                                      value-length
us-ascii       US-ASCII                     value
0x48           natural-language type        value-tag
0x001B                                      name-length
attributes-    attributes-natural-language  name
natural-
language
0x0005                                      value-length
en-us          en-US                        value
0x45           uri type                     value-tag
0x000B                                      name-length
printer-uri    printer-uri                  name
0x0015                                      value-length
ipp://forest/p printer pinetree             value


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Octets         Symbolic Value               Protocol field

inetree
0x03           end-of-attributes            end-of-attributes-tag


13.7 Get-Jobs Request

The following is an example of Get-Jobs request with parameters but no
attributes:


Octets           Symbolic Value               Protocol field

0x0101           1.1                          version-number
0x000A           Get-Jobs                     operation-id
0x00000123       0x123                        request-id
0x01             start operation-attributes   operation-attributes-tag
0x47             charset type                 value-tag
0x0012                                        name-length
attributes-      attributes-charset           name
charset
0x0008                                        value-length
us-ascii         US-ASCII                     value
0x48             natural-language type        value-tag
0x001B                                        name-length
attributes-      attributes-natural-language  name
natural-
language
0x0005                                        value-length
en-us            en-US                        value
0x45             uri type                     value-tag
0x000B                                        name-length
printer-uri      printer-uri                  name
0x0015                                        value-length
ipp://forest/pi  printer pinetree             value
netree
0x21             integer type                 value-tag
0x0005                                        name-length
limit            limit                        name
0x0004                                        value-length
0x00000032       50                           value
0x44             keyword type                 value-tag
0x0014                                        name-length
requested-       requested-attributes         name
attributes
0x0006                                        value-length


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Octets           Symbolic Value               Protocol field

job-id           job-id                       value
0x44             keyword type                 value-tag
0x0000           additional value             name-length
0x0008                                        value-length
job-name         job-name                     value
0x44             keyword type                 value-tag
0x0000           additional value             name-length
0x000F                                        value-length
document-format  document-format              value
0x03             end-of-attributes            end-of-attributes-tag


13.8 Get-Jobs Response

The following is an of Get-Jobs response from previous request with 3
jobs. The Printer returns no information about the second job (because
of security reasons):


Octets           Symbolic Value                Protocol field

0x0101           1.1                           version-number
0x0000           successful-ok                 status-code
0x00000123       0x123                         request-id (echoed
                                               back)
0x01             start operation-attributes    operation-attribute-tag
0x47             charset type                  value-tag
0x0012                                         name-length
attributes-      attributes-charset            name
charset
0x000A                                         value-length
ISO-8859-1       ISO-8859-1                    value
0x48             natural-language type         value-tag
0x001B                                         name-length
attributes-      attributes-natural-language   name
natural-
language
0x0005                                         value-length
en-us            en-US                         value
0x41             textWithoutLanguage type      value-tag
0x000E                                         name-length
status-message   status-message                name
0x000D                                         value-length
successful-ok    successful-ok                 value
0x02             start job-attributes (1st     job-attributes-tag


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Octets           Symbolic Value                Protocol field

                 object)
0x21             integer type                  value-tag
0x0006                                         name-length
job-id           job-id                        name
0x0004                                         value-length
147              147                           value
0x36             nameWithLanguage              value-tag
0x0008                                         name-length
job-name         job-name                      name
0x000C                                         value-length
0x0005                                         sub-value-length
fr-ca            fr-CA                         value
0x0003                                         sub-value-length
fou              fou                           name
0x02             start job-attributes (2nd     job-attributes-tag
                 object)
0x02             start job-attributes (3rd     job-attributes-tag
                 object)
0x21             integer type                  value-tag
0x0006                                         name-length
job-id           job-id                        name
0x0004                                         value-length
148              149                           value
0x36             nameWithLanguage              value-tag
0x0008                                         name-length
job-name         job-name                      name
0x0012                                         value-length
0x0005                                         sub-value-length
de-CH            de-CH                         value
0x0009                                         sub-value-length
isch guet        isch guet                     name
0x03             end-of-attributes             end-of-attributes-tag

14. Appendix B: Registration of MIME Media Type Information for
"application/ipp"

This appendix contains the information that IANA requires for
registering a MIME media type.  The information following this paragraph
will be forwarded to IANA to register application/ipp whose contents are
defined in Section 3 "Encoding of  the Operation Layer"  in this
document:

MIME type name: application

MIME subtype name: ipp


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A Content-Type of "application/ipp" indicates an Internet Printing
Protocol message body (request or response). Currently there is one
version: IPP/1.1, whose syntax is described in Section 3 "Encoding of
the Operation Layer"  of [ipp-pro], and whose semantics are described in
[ipp-mod].

Required parameters:  none

Optional parameters:  none

Encoding considerations:

IPP/1.1 protocol requests/responses MAY contain long lines and ALWAYS
contain binary data (for example attribute value lengths).

Security considerations:

IPP/1.1 protocol requests/responses do not introduce any security risks
not already inherent in the underlying transport protocols. Protocol
mixed-version interworking rules in [ipp-mod] as well as protocol
encoding rules in [ipp-pro] are complete and unambiguous.

Interoperability considerations:

IPP/1.1 requests (generated by clients) and responses (generated by
servers) MUST comply with all conformance requirements imposed by the
normative specifications [ipp-mod] and [ipp-pro]. Protocol encoding
rules specified in [ipp-pro] are comprehensive, so that interoperability
between conforming implementations is guaranteed (although support for
specific optional features is not ensured). Both the "charset" and
"natural-language" of all IPP/1.1 attribute values which are a
LOCALIZED-STRING  are explicit within IPP protocol requests/responses
(without recourse to any external information in HTTP, SMTP, or other
message transport headers).

Published specifications:

[ipp-mod]       Isaacson, S., deBry, R., Hastings, T., Herriot, R.,
       Powell, P., "Internet Printing Protocol/1.1: Model and
       Semantics" draft-ietf-ipp-model-v11-07.txt, May 22, 2000.

[ipp-pro]       Herriot, R., Butler, S., Moore, P., Turner, R.,
       "Internet Printing Protocol/1.1: Encoding and Transport", draft-
       ietf-ipp-protocol-v11-06.txt, May 30, 2000.

Applications which use this media type:




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Internet Printing Protocol (IPP) print clients and print servers,
communicating using HTTP/1.1 (see [IPP-PRO]), SMTP/ESMTP, FTP, or other
transport protocol. Messages of type "application/ipp" are self-
contained and transport-independent, including "charset" and "natural-
language" context for any LOCALIZED-STRING value.

Person & email address to contact for further information:

Tom Hastings
Xerox Corporation
 737 Hawaii St. ESAE-231
El Segundo, CA

Phone: 310-333-6413
Fax: 310-333-5514
Email: hastings@cp10.es.xerox.com

or

Robert Herriot
Xerox Corporation
3400 Hillview Ave., Bldg #1
Palo Alto, CA 94304

Phone: 650-813-7696
Fax: 650-813-6860
Email: robert.herriot@pahv.xerox.com

Intended usage:

COMMON


15. Appendix C: Changes from IPP/1.0

IPP/1.1 is identical to IPP/1.0 [RFC2565] with the follow changes:

1.Attributes values that identify a printer or job object use a new
  'ipp' scheme.  The 'http' and 'https' schemes are supported only for
  backward compatibility.  See section 5.

2.Clients MUST support of Digest Authentication, IPP Printers SHOULD
  support Digest Authentication.  See Section 8.1.1

3.TLS is recommended for channel security.  In addition, SSL3 may be
  supported for backward compatibility.  See Section 8.1.2




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4.It is recommended that IPP/1.1 objects accept any request with major
  version number '1'.  See section 9.1.

5.IPP objects SHOULD return the URL scheme requested for "job-printer-
  uri" and "job-uri" Job Attributes, rather than the URL scheme used to
  create the job.   See section 9.2.

6.The IANA and Internationalization sections have been added.  The
  terms "private use" and "experimental" have been changed to "vendor
  extension".  The reserved allocations for attribute group tags,
  attribute syntax tags, and out-of-band attribute values have been
  clarified as to which are reserved to future IETF standards track
  documents and which are reserved to vendor extension.   Both kinds of
  extensions use the type2 registration procedures as defined in [ipp-
  mod].

7.Clarified that future "out-of-band" value definitions may use the
  value field if additional information is needed.


16. Full Copyright Statement

The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to  pertain
to the implementation or use of the technology described in this
document or the extent to which any license under such rights might or
might not be available; neither does it represent that it has made any
effort to identify any such rights.  Information on the IETF's
procedures with respect to rights in standards-track and standards-
related documentation can be found in BCP-11[BCP-11].  Copies of claims
of rights made available for publication and any assurances of licenses
to be made available, or the result of an attempt made to obtain a
general license or permission for the use of such proprietary rights by
implementers or users of this specification can be obtained from the
IETF Secretariat.

The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary rights
which may cover technology that may be required to practice this
standard.  Please address the information to the IETF Executive
Director.

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

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it or
assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,


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provided that the above copyright notice and this paragraph are included
on all such copies and derivative works.  However, this document itself
may not be modified in any way, such as by removing the copyright notice
or references to the Internet Society or other Internet organizations,
except as needed for the  purpose of developing Internet standards in
which case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to translate it into
languages other than English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.
































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