Content Feature Schema for Internet Fax
RFC 2531

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Network Working Group                                         G. Klyne
Request for Comments: 2531                    5GM/Content Technologies
Category: Standards Track                                  L. McIntyre
                                                     Xerox Corporation
                                                            March 1999

                Content Feature Schema for Internet Fax

Status of this Memo

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

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This document defines a content feature schema that is a profile of
   the media feature registration mechanisms [1,2,3] for use in
   performing capability identification between extended Internet fax
   systems [5].

   This document does not describe any specific mechanisms for
   communicating capability information, but does presume that any such
   mechanisms will transfer textual values.  It specifies a textual
   format to be used for describing Internet fax capability information.

Klyne & McIntyre            Standards Track                     [Page 1]
RFC 2531        Content Feature Schema for Internet Fax       March 1999

Table of Contents

   1. Introduction .............................................3
   1.1 Organization of this document............................3
   1.2 Terminology and document conventions.....................3
   2. Fax feature schema syntax ................................4
   3. Internet fax feature tags ................................4
   3.1 Image size...............................................5
   3.2 Resolution...............................................5
   3.3 Media type...............................................6
   3.4 Paper Size...............................................6
   3.5 Color capability.........................................6
   3.6 Color model..............................................8
   3.7 Image coding............................................10
   4. Examples ................................................12
   4.1 Simple mode Internet fax system.........................12
   4.2 High-end black-and-white Internet fax system............12
   4.3 Grey-scale Internet fax system..........................13
   4.4 Full-color Internet fax system..........................13
   4.5 Full-color Internet fax system (MRC)....................14
   4.6 Sender and receiver feature matching....................15
   5. IANA Considerations .....................................17
   6. Security Considerations .................................17
   6.1 Capability descriptions and mechanisms..................17
   6.2 Specific threats........................................18
   7. Acknowledgements ........................................18
   8. References ..............................................18
   9. Authors' Addresses ......................................21
   Appendix A: Feature registrations ..........................22
   A.1 Image size..............................................22
   A.2 Resolution aspect ratio.................................24
   A.3 Color levels............................................25
   A.4 Color space.............................................27
   A.5 CIELAB color depth......................................30
   A.6 CIELAB color gamut......................................32
   A.7 Image file structure....................................34
   A.8 Image data coding.......................................36
   A.9 Image coding constraint.................................38
   A.10 JBIG stripe size.......................................39
   A.11 Image interleave.......................................41
   A.12 Color subsampling......................................42
   A.13 MRC availability and mode..............................43
   A.14 MRC maximum stripe size................................45
   Appendix B: TIFF mode descriptions .........................47
   Appendix C: Revision history ...............................49
   Full Copyright Statement ...................................51

Klyne & McIntyre            Standards Track                     [Page 2]
RFC 2531        Content Feature Schema for Internet Fax       March 1999

1. Introduction

   This document defines a content feature schema that is a profile of
   the media feature registration mechanisms [1,2,3] for use in
   performing capability identification between extended Internet fax
   systems [5].

   This document does not describe any specific mechanisms for
   communicating capability information, but does presume that any such