Internet Printing Protocol/1.1: IPP URL Scheme
draft-ietf-ipp-url-scheme-04

Internet Printing Protocol Working Group                     Bob Herriot
INTERNET DRAFT                                                Consultant
<draft-ietf-ipp-url-scheme-04.txt>                          Ira McDonald
Updates: RFC 2910                                         High North Inc
[Target Category: Standards Track]                       10 January 2002
Expires 10 July 2002

                             IPP URL Scheme
                   <draft-ietf-ipp-url-scheme-04.txt>

    Copyright (C) The Internet Society (2002). 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
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   To view the list of Internet-Draft Shadow Directories, see
   http://www.ietf.org/shadow.html.  

Abstract 

   This memo defines the "ipp" URL scheme for registration by IANA in
   the IETF tree.  This memo fully conforms to the requirements in
   [RFC2717].  The "ipp" URL (Uniform Resource Locator) scheme is used
   for specifying the location of an IPP Printer, IPP Job, or other IPP
   object (defined in any future version of IPP) which implements the
   IPP/1.1 Model [RFC2911] and the IPP/1.1 Protocol encoding over HTTP
   [RFC2910] or any later version of IPP.  The intended usage of the
   "ipp" URL scheme is COMMON.  

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                           Table of Contents

1.  Introduction ...............................................       3
2.  Terminology ................................................       4
  2.1.  Conformance Terminology ................................       4
  2.2.  Model Terminology ......................................       4
3.  IPP Model for Printers and Jobs ............................       5
4.  IPP URL Scheme .............................................       6
  4.1.  Applicability and Intended Usage .......................       6
  4.2.  Associated IPP Port ....................................       6
  4.3.  Associated IPP MIME Type ...............................       6
  4.4.  Character Encoding .....................................       6
  4.5.  Syntax in ABNF .........................................       7
    4.5.1.  IPP URL Examples ...................................       8
    4.5.2.  IPP URL Comparisons ................................       9
5.  Conformance Requirements ...................................      10
  5.1.  Conformance Requirements for IPP Clients ...............      10
  5.2.  Conformance Requirements for IPP Printers ..............      10
6.  IANA Considerations ........................................      11
7.  Internationalization Considerations ........................      11
8.  Security Considerations ....................................      11
9.  References .................................................      12
10.  Acknowledgments ...........................................      12
11.  Authors' Addresses ........................................      13
12.  Full Copyright Statement ..................................      14
13.  Appendix X - Change History ...............................      15

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1.  Introduction

   See section 1 'Introduction' in [RFC2911] for a full description of
   the IPP document set and overview information about IPP.  
   
   This memo defines the "ipp" URL scheme for registration by IANA in
   the IETF tree.  This memo fully conforms to the requirements in
   [RFC2717].  The "ipp" URL (Uniform Resource Locator) scheme is used
   for specifying the location of an IPP Printer, IPP Job, or other IPP
   object (defined in any future version of IPP) which implements the
   IPP/1.1 Model [RFC2911] and the IPP/1.1 Protocol encoding over HTTP
   [RFC2910] or any later version of IPP.  The intended usage of the
   "ipp" URL scheme is COMMON.  
   
   The IPP URL scheme defined in this document is based on the ABNF for
   the HTTP URL scheme defined in HTTP/1.1 [RFC2616], which is derived
   from the URI Generic Syntax [RFC2396] and further updated by
   [RFC2732] and [RFC2373] (for IPv6 addresses in URLs).  An IPP URL is
   transformed into an HTTP URL according to the rules specified in
   section 5 of the IPP/1.1 Encoding and Transport [RFC2910].  
   
   This document defines:  
   - IPP URL scheme applicability and intended usage; 
   - IPP URL scheme associated port (i.e., well-known port 631); 
   - IPP URL scheme associated MIME type (i.e., "application/ipp"); 
   - IPP URL scheme character encoding; 
   - IPP URL scheme syntax in ABNF [RFC2234]; 
   - IPP URL scheme IANA, internationalization, and security
     considerations.  
   
   This document is laid out as follows:  
   - Section 2 is the terminology used throughout the document.  
     
   - Section 3 provides references to the IPP Printer and IPP Job object
     model.  
     
   - Section 4 specifies the IPP URL scheme.  
     
   - Section 5 specifies the conformance requirements for IPP Clients
     and IPP Printers that claim conformance to this document.  
     
   - Sections 6, 7, and 8 specify IANA, internationalization, and
     security considerations.  
     
   - Sections 9, 10, 11, and 12 list references, acknowledgements,
     authors' addresses, and full IETF copyright statement.  

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2.  Terminology

   This specification document uses the terminology defined in this
   section.  
   
   
   2.1.  Conformance Terminology
   
   The uppercase terms "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
   NOT" "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
   this document are to be interpreted as described in [RFC2119].  These
   terms are used to specify conformance requirements for all
   implementations of this specification.  
   
   
   2.2.  Model Terminology
   
   See section 12.2 'Model Terminology' in [RFC2911].  

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3.  IPP Model for Printers and Jobs

   See section 2 'IPP Objects', section 2.1 'Printer Object', and
   section 2.2 'Job Object' in [RFC2911] for a full description of the
   IPP object model and terminology.  
   
   In this document, "IPP Client" means the software (on some hardware
   platform) that submits, monitors, and/or manages print jobs via
   IPP/1.1 [RFC2910] [RFC2911], or any later version of IPP to a
   spooler, gateway, or actual printing device.  
   
   In this document, "IPP Printer object" means the software (on some
   hardware platform) that receives print jobs and/or printer/job
   operations via IPP/1.1 [RFC2910] [RFC2911], or any later version of
   IPP from an "IPP Client".  
   
   In this document, "IPP Printer" is a synonym for "IPP Printer
   object".  
   
   In this document, "IPP Job object" means the set of attributes and
   documents for one print job on an "IPP Printer".  
   
   In this document, "IPP Job" is a synonym for "IPP Job object".  
   
   In this document, "IPP URL" means a URL with the "ipp" scheme.  
   
   Note:  In this document, "IPP URL" is a synonym for "ipp_URL" (in
   section 4 'IPP URL Scheme' of this document) and "ipp-URL" (in
   section 5 'IPP URL Scheme' of [RFC2910]).  

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4.  IPP URL Scheme

   
   
   4.1.  Applicability and Intended Usage
   
   This memo defines the "ipp" URL scheme for registration by IANA in
   the IETF tree.  This memo fully conforms to the requirements in
   [RFC2717].  The "ipp" URL (Uniform Resource Locator) scheme is used
   for specifying the location of an IPP Printer, IPP Job, or other IPP
   object (defined in any future version of IPP) which implements the
   IPP/1.1 Model [RFC2911] and the IPP/1.1 Protocol encoding over HTTP
   [RFC2910] or any later version of IPP.  The intended usage of the
   "ipp" URL scheme is COMMON.  
   
   
   
   4.2.  Associated IPP Port
   
   All IPP URLs which do NOT explicitly specify a port MUST be used over
   IANA-assigned well-known port 631, as registered in [IANA-PORTREG].  
   
   See:  IANA Port Numbers Registry [IANA-PORTREG].  
   See:  IPP Encoding and Transport [RFC2910].  
   
   
   
   4.3.  Associated IPP MIME Type
   
   All IPP protocol operations (requests and responses) MUST be conveyed
   in an "application/ipp" MIME media type as registered in
   [IANA-MIMEREG].  IPP URLs MUST refer to IPP Printers which support
   this "application/ipp" MIME media type.  
   
   See:  IANA MIME Media Types Registry [IANA-MIMEREG].  
   See:  IPP Encoding and Transport [RFC2910].  
   
   
   
   4.4.  Character Encoding
   
   The IPP URL scheme defined in this document is based on the ABNF for
   the HTTP URL scheme defined in HTTP/1.1 [RFC2616], which is derived
   from the URI Generic Syntax [RFC2396] and further updated by
   [RFC2732] and [RFC2373] (for IPv6 addresses in URLs).  An IPP URL is
   transformed into an HTTP URL according to the rules specified in
   section 5 of the IPP/1.1 Encoding and Transport [RFC2910].  
   
   The IPP URL scheme is case-insensitive in the host name or host

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   address part; however the path part is case-sensitive, as in
   [RFC2396].  Codepoints outside [US-ASCII] MUST be hex escaped by the
   mechanism specified in [RFC2396].  
   
   
   
   4.5.  Syntax in ABNF
   
   Note:  In this document, "IPP URL" is a synonym for "ipp_URL" (in
   section 4 'IPP URL Scheme' of this document) and "ipp-URL" (in
   section 5 'IPP URL Scheme' of [RFC2910]).  
   
   This memo defines the "ipp" URL scheme for registration by IANA in
   the IETF tree.  This memo fully conforms to the requirements in
   [RFC2717].  The "ipp" URL (Uniform Resource Locator) scheme is used
   for specifying the location of an IPP Printer, IPP Job, or other IPP
   object (defined in any future version of IPP) which implements the
   IPP/1.1 Model [RFC2911] and the IPP/1.1 Protocol encoding over HTTP
   [RFC2910] or any later version of IPP.  The intended usage of the
   "ipp" URL scheme is COMMON.  
   
   The IPP protocol places a limit of 1023 octets (NOT characters) on
   the length of a URI (see section 4.1.5 'uri' in [RFC2911]).  An IPP
   Printer MUST return 'client-error-request-value-too-long' (see
   section 13.1.4.10 in [RFC2911]) when a URI received in a request
   (e.g., in the "printer-uri" attribute) is too long.  
   
      Note:  IPP Printers ought to be cautious about depending on URI
      lengths above 255 bytes, because some older client implementations
      might not properly support these lengths.  
   
   IPP URLs MUST be represented in absolute form.  Absolute URLs always 
   begin with a scheme name followed by a colon.  For definitive
   information on URL syntax and semantics, see "Uniform Resource
   Identifiers (URI): Generic Syntax and Semantics" [RFC2396].  This
   specification adopts the definitions of "host", "port", "abs_path",
   "rel_path", and "query" from [RFC2396], as updated by [RFC2732] and
   [RFC2373] (for IPv6 addresses in URLs).  
   
   The IPP URL scheme syntax in ABNF is as follows:  
   
   ipp_URL = "ipp:" "//" host [ ":" port ] [ abs_path [ "?" query ]]
   
   If the port is empty or not given, port 631 is assumed.  The
   semantics are that the identified resource (see section 5.1.2 of
   [RFC2616]) is located at the IPP Printer or IPP Job listening for
   HTTP connections on that port of that host, and the Request-URI for
   the identified resource is 'abs_path'.  
   
   If the 'abs_path' is not present in the URL, it MUST be given as "/" 
   when used as a Request-URI for a resource (see section 5.1.2 of

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   [RFC2616]).  
   
   
   
   4.5.1.  IPP URL Examples
   
   The following are examples of valid IPP URLs for IPP Printers:  
   
       ipp://abc.com
       ipp://abc.com/printer
       ipp://abc.com/tiger
       ipp://abc.com/printers/tiger
       ipp://abc.com/printers/fox
       ipp://abc.com/printers/tiger/bob
       ipp://abc.com/printers/tiger/ira
       ipp://printer.abc.com
       ipp://printers.abc.com/tiger
       ipp://printers.abc.com/tiger/bob
       ipp://printers.abc.com/tiger/ira
   
   Each of the above URLs are legitimate URLs for IPP Printers and each 
   references a logically different IPP Printer, even though some of the
   IPP Printers may share the same hardware.  The last part of the path 
   'bob' or 'ira' may represent two different hardware devices where
   'tiger' represents some grouping of IPP Printers (e.g., a
   load-balancing spooler) or the two names may represent separate human
   recipients ('bob' and 'ira') on the same hardware device (e.g., a
   printer supporting two job queues).  In either case both 'bob' and
   'ira' behave as different IPP Printers.  
   
   The following are examples of IPP URLs with (optional) ports and
   paths:  
   
       ipp://abc.com
       ipp://abc.com/~smith/printer
       ipp://abc.com:631/~smith/printer
   
   The first and second IPP URLs above MUST be resolved to port 631
   (IANA assigned well-known port for IPP).  The second and third IPP
   URLs above are equivalent (see section 4.5.2 below).  
   
   The following literal IPv4 addresses:  
   
       192.9.5.5                           ; IPv4 address in IPv4 style
       186.7.8.9                           ; IPv4 address in IPv4 style
   
   are represented in the following example IPP URLs:  
   
       ipp://192.9.5.5/prt1
       ipp://186.7.8.9/printers/tiger/bob

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   The following literal IPv6 addresses (conformant to [RFC2373]):  
   
       ::192.9.5.5                         ; IPv4 address in IPv6 style
       ::FFFF:129.144.52.38                ; IPv4 address in IPv6 style
       2010:836B:4179::836B:4179           ; IPv6 address per RFC 2373
   
   are represented in the following example IPP URLs:  
   
       ipp://[::192.9.5.5]/prt1
       ipp://[::FFFF:129.144.52.38]:631/printers/tiger
       ipp://[2010:836B:4179::836B:4179]/printers/tiger/bob
   
   
   
   4.5.2.  IPP URL Comparisons
   
   When comparing two IPP URLs to decide if they match or not, an IPP
   Client MUST use the same rules as those defined for HTTP URI
   comparisons in [RFC2616], with the sole following exception:  
   
   - A port that is empty or not given MUST be treated as equivalent to
     the well-known port for that IPP URL (port 631);
   
   See:  Section 3.2.3 'URI Comparison' in [RFC2616].  

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5.  Conformance Requirements

   
   
   5.1.  Conformance Requirements for IPP Clients
   
   IPP Clients that conform to this specification:  
   
   a) MUST send IPP URLs (e.g., in the "printer-uri" operation attribute
      in 'Print-Job') that conform to the ABNF specified in section 4.5 
      of this document; 
      
   b) MUST send IPP operations via the port specified in the IPP URL (if
      present) or otherwise via IANA assigned well-known port 631; 
      
   c) MUST convert IPP URLs to their corresponding HTTP URL forms
      according to the rules in section 5 'IPP URL Scheme' in [RFC2910];
      
   d) SHOULD interoperate with IPP/1.0 Printers according to the rules
      in section 9 'Interoperability with IPP/1.0 Implementations' and
      section 9.2 'Security and URL Schemes' in [RFC2910].  
   
   
   
   5.2.  Conformance Requirements for IPP Printers
   
   IPP Printers that conform to this specification:  
   
   a) SHOULD reject received IPP URLs in "application/ipp" request
      bodies (e.g., in the "printer-uri" attribute in a 'Print-Job'
      request) that do not conform to the ABNF for IPP URLs specified in
      section 4.5 of this document; 
      
   b) SHOULD return IPP URLs in "application/ipp" response bodies (e.g.,
      in the "job-uri" attribute in a 'Print-Job' response) that do
      conform to the ABNF for IPP URLs specified in section 4.5 of this 
      document; 
      
   c) MUST listen for IPP operations on IANA-assigned well-known port
      631, unless explicitly configured by system administrators or site
      policies; 
      
   d) SHOULD NOT listen for IPP operations on any other port, unless
      explicitly configured by system administrators or site policies; 
      
   e) SHOULD interoperate with IPP/1.0 Clients according to the rules in
      section 9 'Interoperability with IPP/1.0 Implementations' and
      section 9.2 'Security and URL Schemes' in [RFC2910].  

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6.  IANA Considerations

   This memo defines the "ipp" URL scheme for registration by IANA in
   the IETF tree.  This memo fully conforms to the requirements in
   [RFC2717].  The "ipp" URL (Uniform Resource Locator) scheme is used
   for specifying the location of an IPP Printer, IPP Job, or other IPP
   object (defined in any future version of IPP) which implements the
   IPP/1.1 Model [RFC2911] and the IPP/1.1 Protocol encoding over HTTP
   [RFC2910] or any later version of IPP.  The intended usage of the
   "ipp" URL scheme is COMMON.  
   
   This IPP URL Scheme specification does not introduce any additional
   IANA considerations, beyond those described in [RFC2910] and
   [RFC2911].  
   
   See:  Section 6 'IANA Considerations' in [RFC2910] 
   See:  Section 6 'IANA Considerations' in [RFC2911].  

7.  Internationalization Considerations

   This IPP URL Scheme specification does not introduce any additional
   internationalization considerations, beyond those described in
   [RFC2910] and [RFC2911].  
   
   See:  Section 7 'Internationalization Considerations' in [RFC2910].  
   See:  Section 7 'Internationalization Considerations' in [RFC2911].  

8.  Security Considerations

   This IPP URL Scheme specification does not introduce any additional
   security considerations, beyond those described in [RFC2910] and
   [RFC2911].  
   
   See:  Section 8 'Security Considerations' in [RFC2910].  
   See:  Section 8 'Security Considerations' in [RFC2911].  

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9.  References

   See:  Section 10 'References' in [RFC2910].  
   
   [IANA-MIMEREG] IANA MIME Media Types Registry.  
   ftp://ftp.iana.org/in-notes/iana/assignments/media-types/...  
   
   [IANA-PORTREG] IANA Port Numbers Registry.  
   ftp://ftp.iana.org/in-notes/iana/assignments/port-numbers 
   
   [RFC2234] D. Crocker, P. Overell.  Augmented BNF for Syntax
   Specifications: ABNF, RFC 2234, November 1997.  
   
   [RFC2373] R. Hinden, S. Deering.  IP Version 6 Addressing
   Architecture, RFC 2373, July 1998.  
   
   [RFC2396] T. Berners-Lee, R. Fielding, L. Masinter.  Uniform Resource
   Identifiers (URI): Generic Syntax, RFC 2396, August 1998.  
   
   [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.  
   
   [RFC2717] R. Petke, I. King.  Registration Procedures for URL Scheme
   Names, RFC 2717, November 1999.  
   
   [RFC2732] R. Hinden,B. Carpenter, L. Masinter.  Format for Literal
   IPv6 Addresses in URL's, RFC 2732, December 1999.  
   
   [RFC2910] R. Herriot, S. Butler, P. Moore, R. Turner, J. Wenn.
   IPP/1.1 Encoding and Transport, RFC 2910, September 2000.  
   
   [RFC2911] T. Hastings, R. Herriot, R. deBry, S. Isaacson, P. Powell.
   IPP/1.1 Model and Semantics, RFC 2911, September 2000.  
   
   [US-ASCII] Coded Character Set -- 7-bit American Standard Code for
   Information Interchange, ANSI X3.4-1986.  

10.  Acknowledgments

   This document is a product of the Internet Printing Protocol Working 
   Group of the Internet Engineering Task Force (IETF).  
   
   Thanks to Pat Fleming (IBM), Tom Hastings (Xerox), Harry Lewis (IBM),
   Hugo Parra (Novell), Don Wright (Lexmark), and all the members of the
   IETF IPP WG.  

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   Section 5 'IPP URL Scheme' in IPP/1.1 Encoding and Transport
   [RFC2910] was the primary input to this IPP URL Scheme specification.

11.  Authors' Addresses

   Robert Herriot
   Consultant
   706 Colorado Ave
   Palo Alto, CA  94303
   
   Phone: +1 650-327-4466
   Fax:   +1 650-327-4466
   Email: bob@herriot.com
   
   
   Ira McDonald
   High North Inc
   221 Ridge Ave
   Grand Marais, MI  49839
   
   Phone: +1 906-494-2434 or +1 906-494-2697
   Email: imcdonald@sharplabs.com
   
   
   Usage questions and comments on this IPP URL Scheme should be sent
   directly to the editors at their above addresses (and to the IPP
   mailing list, if you are a subscriber - see below).  
   
   
   IPP Web Page:      http://www.pwg.org/ipp/
   IPP Mailing List:  ipp@pwg.org
   
   To subscribe to the IPP mailing list, send the following email:
     1) send it to majordomo@pwg.org
     2) leave the subject line blank
     3) put the following two lines in the message body:
          subscribe ipp
          end
   
   Implementers of this specification are encouraged to join the IPP
   Mailing List in order to participate in any discussions of
   clarification issues and comments.  In order to reduce spam the
   mailing list rejects mail from non-subscribers, so you must subscribe
   to the mailing list in order to send a question or comment to the IPP
   mailing list.  

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12.  Full Copyright Statement

   Copyright (C) The Internet Society (2002).  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, 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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13.  Appendix X - Change History

   [To be deleted before RFC publication] 
   
   10 January 2002 - draft-ietf-ipp-url-scheme-04.txt 
   - final edits after IESG 'last call' comments; 
   - revised all titles in sections 4.x to remove redundant prefix of
     'IPP URL Scheme', for readability; 
   - revised 'Abstract', section 1 'Introduction', section 4.1
     'Applicability and Intended Usage', section 4.5 'Syntax in ABNF',
     and section 6 'IANA Considerations', to explicitly state that the
     "ipp" URL scheme is intended for IANA registration in the IETF URL
     scheme tree; 
   - revised section 4.5 'Syntax in ABNF', to delete references to
     unused ABNF components from [RFC2396]; 
   - revised section 11 'Authors' Addresses', to update contact info for
     both editors and to add the IPP Web page and mailing list
     subscription info; 
   - moved 'Appendix X - Change History' to back of document, to
     facilitate final edits for RFC publication (including deletion of
     change history); 
   
   2 April 2001 - draft-ietf-ipp-url-scheme-03.txt 
   - final edits after IETF IPP WG 'last call' comments; 
   - revised 'Abstract' and section 1 'Introduction' to remove
     references to ISSUE's and request for comments to the 'ipp@pwg.org'
     mailing list, in preparation for publication as an RFC; 
   - revised section 4.5 'IPP URL Scheme Syntax in ABNF' to delete all
     references to HTTP proxy behavior (which IPP does NOT specify), per
     request of Don Wright; 
   - revised section 4.5.1 'IPP URL Examples' to remove note
     discouraging the use of literal IP addresses in URLs, to remove
     dependency on Informational [RFC1900]; 
   - revised section 4.5.2 'IPP URL Comparisons' to specify the use of
     rules defined in section 3.2.3 'URI Comparison' in [RFC2616], with 
     the sole exception that an empty port MUST be treated as equivalent
     to the IPP well-known port 631, per request of Don Wright; 
   - revised section 9 'References' to delete all unused references; 
   - revised section 11 'Authors' Addresses' to add the address of the
     IPP WG mailing list for usage questions and comments; 
   
   13 February 2001 - draft-ietf-ipp-url-scheme-02.txt 
   - revised section 3 'IPP Model for Printers and Jobs' and section 4.5
     'IPP URL Scheme Syntax in ABNF' to add notes stating that "IPP URL"
     (in this document) is a synonym for "ipp-URL" in [RFC2910], per
     request of Bob Herriot; 
   - revised section 4.5 'IPP URL Scheme Syntax in ABNF' to correct typo
     that showed "http:" rather than "ipp:" in the one-line ABNF, per
     request of Tom Hastings; 

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   - revised section 4.5.1 'IPP URL Examples' to add a note discouraging
     the use of literal IP addresses in URLs, per [RFC2616] and
     [RFC1900]; 
   
   5 February 2001 - draft-ietf-ipp-url-scheme-01.txt 
   - revised section 4.1 'IPP URL Applicability and Intended Usage' to
     clarify that a given IPP URL MAY identify an IPP Printer object or 
     an IPP Job object, per request of Tom Hastings; 
   - revised section 4.5 'IPP URL Scheme Syntax in ABNF' to define IPP
     URLs consistently with section 3.2.2 'http URL' of HTTP/1.1
     [RFC2616], per request of Tom Hastings; 
   - revised section 4.5 'IPP URL Scheme Syntax in ABNF' to clarify that
     IPP URLs may reference IPP Printer objects, IPP Job objects, or
     (possibly other future) IPP objects, per request of Bob Herriot; 
   - added section 4.5.1 'IPP URL Examples' to supply meaningful
     examples of IPP URLs with host names, IPv4 addresses, and IPv6
     addresses, per request of Tom Hastings; 
   - added section 4.5.2 'IPP URL Comparisons' to define IPP URL
     comparisons consistently with section 3.3 'URI Comparison' of
     HTTP/1.1 [RFC2616], per request of Tom Hastings; 
   - revised section 5.1 'Conformance Requirements for IPP Clients' to
     clarify that an IPP Client MUST convert IPP URLs to their
     corresponding HTTP URL forms according to section 5 'IPP URL
     Scheme' in [RFC2910], per request of Tom Hastings and Bob Herriot; 
   - revised section 5.1 'Conformance Requirements for IPP Clients' and
     section 5.2 'Conformance Requirements for IPP Printers' to clarify
     that IPP Clients and IPP Printers SHOULD interoperate with IPP/1.0
     systems according to section 9 'Interoperability with IPP/1.0
     Implementations' in [RFC2910], per request of Carl Kugler; 
   - revised section 5.2 'Conformance Requirements for IPP Printers' to 
     clarify that an IPP Printer MUST listen on (IANA assigned
     well-known) port 631, unless explicitly configured, per request of
     Michael Sweet; 
   - revised section 5.2 'Conformance Requirements for IPP Printers' to 
     clarify that an IPP Printer SHOULD NOT listen on ports other than
     (IANA assigned well-known) port 631, unless explicitly configured, 
     per request of Don Wright; 
   - revised section 6 'IANA Considerations' to clarify that the sole
     purpose of the entire document is IANA registration of the "ipp"
     URL scheme; 
   - deleted Appendix A 'Registration of IPP Port' as unnecessary (port
     is already registered); 
   - deleted Appendix B 'Registration of MIME "application/ipp" as
     unnecessary (MIME registry has recently caught up to RFC 2910); 
   
   11 January 2001 - draft-ietf-ipp-url-scheme-00.txt 
   - initial version - simple "ipp" URL scheme without parameters or
     query part (consistent with existing and IPP/1.1 implementations); 
   - added Appendix A 'Registration of IPP Port' (placeholder) for
     updated IANA registration of port 631 with references to IPP/1.1; 

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   - added Appendix B 'Registration of MIME "application/ipp"' with
     updated IANA registration for IPP MIME type with references to both
     IPP/1.0 and IPP/1.1; 
   

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