Network Working Group                                 M. Nottingham, Ed.
Request for Comments: 4287                                 R. Sayre, Ed.
Category: Standards Track                                  December 2005


                      The Atom Syndication Format

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 (2005).

Abstract

   This document specifies Atom, an XML-based Web content and metadata
   syndication format.

Table of Contents

   1. Introduction ....................................................3
      1.1. Examples ...................................................3
      1.2. Namespace and Version ......................................5
      1.3. Notational Conventions .....................................5
   2. Atom Documents ..................................................6
   3. Common Atom Constructs ..........................................7
      3.1. Text Constructs ............................................7
           3.1.1. The "type" Attribute ................................8
      3.2. Person Constructs .........................................10
           3.2.1. The "atom:name" Element ............................10
           3.2.2. The "atom:uri" Element .............................10
           3.2.3. The "atom:email" Element ...........................10
      3.3. Date Constructs ...........................................10
   4. Atom Element Definitions .......................................11
      4.1. Container Elements ........................................11
           4.1.1. The "atom:feed" Element ............................11
           4.1.2. The "atom:entry" Element ...........................13
           4.1.3. The "atom:content" Element .........................14
      4.2. Metadata Elements .........................................17
           4.2.1. The "atom:author" Element ..........................17
           4.2.2. The "atom:category" Element ........................18
           4.2.3. The "atom:contributor" Element .....................18



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RFC 4287                      Atom Format                  December 2005


           4.2.4. The "atom:generator" Element .......................18
           4.2.5. The "atom:icon" Element ............................19
           4.2.6. The "atom:id" Element ..............................19
           4.2.7. The "atom:link" Element ............................21
           4.2.8. The "atom:logo" Element ............................23
           4.2.9. The "atom:published" Element .......................23
           4.2.10. The "atom:rights" Element .........................24
           4.2.11. The "atom:source" Element .........................24
           4.2.12. The "atom:subtitle" Element .......................25
           4.2.13. The "atom:summary" Element ........................25
           4.2.14. The "atom:title" Element ..........................25
           4.2.15. The "atom:updated" Element ........................25
   5. Securing Atom Documents ........................................26
      5.1. Digital Signatures ........................................26
      5.2. Encryption ................................................27
      5.3. Signing and Encrypting ....................................28
   6. Extending Atom .................................................28
      6.1. Extensions from Non-Atom Vocabularies .....................28
      6.2. Extensions to the Atom Vocabulary .........................28
      6.3. Processing Foreign Markup .................................28
      6.4. Extension Elements ........................................29
           6.4.1. Simple Extension Elements ..........................29
           6.4.2. Structured Extension Elements ......................29
   7. IANA Considerations ............................................30
      7.1. Registry of Link Relations ................................31
   8. Security Considerations ........................................31
      8.1. HTML and XHTML Content ....................................31
      8.2. URIs ......................................................31
      8.3. IRIs ......................................................31
      8.4. Spoofing ..................................................31
      8.5. Encryption and Signing ....................................32
   9. References .....................................................32
      9.1. Normative References ......................................32
      9.2. Informative References ....................................34
   Appendix A. Contributors ..........................................35
   Appendix B. RELAX NG Compact Schema ...............................35















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