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RFC 4287 - The Atom Syndication Format
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<meta name="savepage-title" content="RFC 4287 - The Atom Syndication Format">
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<meta name="savepage-pubdate" content="Unknown">
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<meta name="savepage-date" content="Fri Mar 04 2022 13:01:54 GMT-0800 (Pacific Standard Time)">
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<pre class="pre meta-info">[<a data-savepage-href="https://datatracker.ietf.org" href="https://datatracker.ietf.org/" title="Document search and retrieval page">Search</a>] [<a href="https://www.rfc-editor.org/rfc/rfc4287.txt" title="Plaintext version of this document">txt</a>|<a href="https://www.rfc-editor.org/rfc/rfc4287.html" title="HTML version of this document, from XML2RFC">html</a>|<a href="https://www.rfc-editor.org/rfc/pdfrfc/rfc4287.txt.pdf" title="PDF version of this document">pdf</a>|<a data-savepage-href="/doc/rfc4287/bibtex/" href="https://datatracker.ietf.org/doc/rfc4287/bibtex/" title="BibTex entry for this document">bibtex</a>] [<a data-savepage-href="/doc/rfc4287/" href="https://datatracker.ietf.org/doc/rfc4287/" title="Datatracker information for this document">Tracker</a>] [<a data-savepage-href="/group/atompub/" href="https://datatracker.ietf.org/group/atompub/" title="The working group handling this document">WG</a>] [<a href="mailto:draft-ietf-atompub-format@ietf.org?subject=draft-ietf-atompub-format" title="Send email to the document authors">Email</a>] [<a href="https://www.ietf.org/rfcdiff?difftype=--hwdiff&url2=draft-ietf-atompub-format-11.txt" title="Inline diff (wdiff)">Diff1</a>] [<a href="https://www.ietf.org/rfcdiff?url2=draft-ietf-atompub-format-11.txt" title="Side-by-side diff">Diff2</a>] [<a href="https://www.ietf.org/tools/idnits?url=https://www.ietf.org/archive/id/draft-ietf-atompub-format-11.txt" title="Run an idnits check of this document">Nits</a>]
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From: <a data-savepage-href="/doc/html/draft-ietf-atompub-format-11" href="https://datatracker.ietf.org/doc/html/draft-ietf-atompub-format-11">draft-ietf-atompub-format-11</a> Proposed Standard
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Updated by: <a data-savepage-href="/doc/html/rfc5988" href="https://datatracker.ietf.org/doc/html/rfc5988">5988</a> <a class="text-warning" data-savepage-href="/ipr/search/?submit=draft&id=draft-ietf-atompub-format" href="https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-ietf-atompub-format">IPR declarations</a></pre>
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</div>
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<div class="draftcontent">
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<pre>Network Working Group M. Nottingham, Ed.
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Request for Comments: 4287 R. Sayre, Ed.
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Category: Standards Track December 2005
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<span class="h1">The Atom Syndication Format</span>
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Status of This Memo
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This document specifies an Internet standards track protocol for the
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Internet community, and requests discussion and suggestions for
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||
improvements. Please refer to the current edition of the "Internet
|
||
Official Protocol Standards" (STD 1) for the standardization state
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and status of this protocol. Distribution of this memo is unlimited.
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Copyright Notice
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Copyright (C) The Internet Society (2005).
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Abstract
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This document specifies Atom, an XML-based Web content and metadata
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syndication format.
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Table of Contents
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<a href="#section-1">1</a>. Introduction ....................................................<a href="#page-3">3</a>
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<a href="#section-1.1">1.1</a>. Examples ...................................................<a href="#page-3">3</a>
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||
<a href="#section-1.2">1.2</a>. Namespace and Version ......................................<a href="#page-5">5</a>
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<a href="#section-1.3">1.3</a>. Notational Conventions .....................................<a href="#page-5">5</a>
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<a href="#section-2">2</a>. Atom Documents ..................................................<a href="#page-6">6</a>
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<a href="#section-3">3</a>. Common Atom Constructs ..........................................<a href="#page-7">7</a>
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<a href="#section-3.1">3.1</a>. Text Constructs ............................................<a href="#page-7">7</a>
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<a href="#section-3.1.1">3.1.1</a>. The "type" Attribute ................................<a href="#page-8">8</a>
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<a href="#section-3.2">3.2</a>. Person Constructs .........................................<a href="#page-10">10</a>
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<a href="#section-3.2.1">3.2.1</a>. The "atom:name" Element ............................<a href="#page-10">10</a>
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<a href="#section-3.2.2">3.2.2</a>. The "atom:uri" Element .............................<a href="#page-10">10</a>
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<a href="#section-3.2.3">3.2.3</a>. The "atom:email" Element ...........................<a href="#page-10">10</a>
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<a href="#section-3.3">3.3</a>. Date Constructs ...........................................<a href="#page-10">10</a>
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<a href="#section-4">4</a>. Atom Element Definitions .......................................<a href="#page-11">11</a>
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<a href="#section-4.1">4.1</a>. Container Elements ........................................<a href="#page-11">11</a>
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<a href="#section-4.1.1">4.1.1</a>. The "atom:feed" Element ............................<a href="#page-11">11</a>
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<a href="#section-4.1.2">4.1.2</a>. The "atom:entry" Element ...........................<a href="#page-13">13</a>
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<a href="#section-4.1.3">4.1.3</a>. The "atom:content" Element .........................<a href="#page-14">14</a>
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<a href="#section-4.2">4.2</a>. Metadata Elements .........................................<a href="#page-17">17</a>
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<a href="#section-4.2.1">4.2.1</a>. The "atom:author" Element ..........................<a href="#page-17">17</a>
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<a href="#section-4.2.2">4.2.2</a>. The "atom:category" Element ........................<a href="#page-18">18</a>
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<a href="#section-4.2.3">4.2.3</a>. The "atom:contributor" Element .....................<a href="#page-18">18</a>
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<span class="grey">Nottingham & Sayre Standards Track [Page 1]</span></pre>
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<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-2"></span>
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<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
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<a href="#section-4.2.4">4.2.4</a>. The "atom:generator" Element .......................<a href="#page-18">18</a>
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<a href="#section-4.2.5">4.2.5</a>. The "atom:icon" Element ............................<a href="#page-19">19</a>
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<a href="#section-4.2.6">4.2.6</a>. The "atom:id" Element ..............................<a href="#page-19">19</a>
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<a href="#section-4.2.7">4.2.7</a>. The "atom:link" Element ............................<a href="#page-21">21</a>
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<a href="#section-4.2.8">4.2.8</a>. The "atom:logo" Element ............................<a href="#page-23">23</a>
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<a href="#section-4.2.9">4.2.9</a>. The "atom:published" Element .......................<a href="#page-23">23</a>
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<a href="#section-4.2.10">4.2.10</a>. The "atom:rights" Element .........................<a href="#page-24">24</a>
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<a href="#section-4.2.11">4.2.11</a>. The "atom:source" Element .........................<a href="#page-24">24</a>
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||
<a href="#section-4.2.12">4.2.12</a>. The "atom:subtitle" Element .......................<a href="#page-25">25</a>
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||
<a href="#section-4.2.13">4.2.13</a>. The "atom:summary" Element ........................<a href="#page-25">25</a>
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||
<a href="#section-4.2.14">4.2.14</a>. The "atom:title" Element ..........................<a href="#page-25">25</a>
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||
<a href="#section-4.2.15">4.2.15</a>. The "atom:updated" Element ........................<a href="#page-25">25</a>
|
||
<a href="#section-5">5</a>. Securing Atom Documents ........................................<a href="#page-26">26</a>
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||
<a href="#section-5.1">5.1</a>. Digital Signatures ........................................<a href="#page-26">26</a>
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||
<a href="#section-5.2">5.2</a>. Encryption ................................................<a href="#page-27">27</a>
|
||
<a href="#section-5.3">5.3</a>. Signing and Encrypting ....................................<a href="#page-28">28</a>
|
||
<a href="#section-6">6</a>. Extending Atom .................................................<a href="#page-28">28</a>
|
||
<a href="#section-6.1">6.1</a>. Extensions from Non-Atom Vocabularies .....................<a href="#page-28">28</a>
|
||
<a href="#section-6.2">6.2</a>. Extensions to the Atom Vocabulary .........................<a href="#page-28">28</a>
|
||
<a href="#section-6.3">6.3</a>. Processing Foreign Markup .................................<a href="#page-28">28</a>
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<a href="#section-6.4">6.4</a>. Extension Elements ........................................<a href="#page-29">29</a>
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||
<a href="#section-6.4.1">6.4.1</a>. Simple Extension Elements ..........................<a href="#page-29">29</a>
|
||
<a href="#section-6.4.2">6.4.2</a>. Structured Extension Elements ......................<a href="#page-29">29</a>
|
||
<a href="#section-7">7</a>. IANA Considerations ............................................<a href="#page-30">30</a>
|
||
<a href="#section-7.1">7.1</a>. Registry of Link Relations ................................<a href="#page-31">31</a>
|
||
<a href="#section-8">8</a>. Security Considerations ........................................<a href="#page-31">31</a>
|
||
<a href="#section-8.1">8.1</a>. HTML and XHTML Content ....................................<a href="#page-31">31</a>
|
||
<a href="#section-8.2">8.2</a>. URIs ......................................................<a href="#page-31">31</a>
|
||
<a href="#section-8.3">8.3</a>. IRIs ......................................................<a href="#page-31">31</a>
|
||
<a href="#section-8.4">8.4</a>. Spoofing ..................................................<a href="#page-31">31</a>
|
||
<a href="#section-8.5">8.5</a>. Encryption and Signing ....................................<a href="#page-32">32</a>
|
||
<a href="#section-9">9</a>. References .....................................................<a href="#page-32">32</a>
|
||
<a href="#section-9.1">9.1</a>. Normative References ......................................<a href="#page-32">32</a>
|
||
<a href="#section-9.2">9.2</a>. Informative References ....................................<a href="#page-34">34</a>
|
||
<a href="#appendix-A">Appendix A</a>. Contributors ..........................................<a href="#page-35">35</a>
|
||
<a href="#appendix-B">Appendix B</a>. RELAX NG Compact Schema ...............................<a href="#page-35">35</a>
|
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<span class="grey">Nottingham & Sayre Standards Track [Page 2]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-3"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
|
||
|
||
Atom is an XML-based document format that describes lists of related
|
||
information known as "feeds". Feeds are composed of a number of
|
||
items, known as "entries", each with an extensible set of attached
|
||
metadata. For example, each entry has a title.
|
||
|
||
The primary use case that Atom addresses is the syndication of Web
|
||
content such as weblogs and news headlines to Web sites as well as
|
||
directly to user agents.
|
||
|
||
<span class="h3"><a class="selflink" id="section-1.1" href="#section-1.1">1.1</a>. Examples</span>
|
||
|
||
A brief, single-entry Atom Feed Document:
|
||
|
||
<?xml version="1.0" encoding="utf-8"?>
|
||
<feed xmlns="http://www.w3.org/2005/Atom">
|
||
|
||
<title>Example Feed</title>
|
||
<link href="http://example.org/"/>
|
||
<updated>2003-12-13T18:30:02Z</updated>
|
||
<author>
|
||
<name>John Doe</name>
|
||
</author>
|
||
<id>urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6</id>
|
||
|
||
<entry>
|
||
<title>Atom-Powered Robots Run Amok</title>
|
||
<link href="http://example.org/2003/12/13/atom03"/>
|
||
<id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
|
||
<updated>2003-12-13T18:30:02Z</updated>
|
||
<summary>Some text.</summary>
|
||
</entry>
|
||
|
||
</feed>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 3]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-4"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
A more extensive, single-entry Atom Feed Document:
|
||
|
||
<?xml version="1.0" encoding="utf-8"?>
|
||
<feed xmlns="http://www.w3.org/2005/Atom">
|
||
<title type="text">dive into mark</title>
|
||
<subtitle type="html">
|
||
A &lt;em&gt;lot&lt;/em&gt; of effort
|
||
went into making this effortless
|
||
</subtitle>
|
||
<updated>2005-07-31T12:29:29Z</updated>
|
||
<id>tag:example.org,2003:3</id>
|
||
<link rel="alternate" type="text/html"
|
||
hreflang="en" href="http://example.org/"/>
|
||
<link rel="self" type="application/atom+xml"
|
||
href="http://example.org/feed.atom"/>
|
||
<rights>Copyright (c) 2003, Mark Pilgrim</rights>
|
||
<generator uri="http://www.example.com/" version="1.0">
|
||
Example Toolkit
|
||
</generator>
|
||
<entry>
|
||
<title>Atom <a data-savepage-href="/doc/html/draft-07" href="https://datatracker.ietf.org/doc/html/draft-07">draft-07</a> snapshot</title>
|
||
<link rel="alternate" type="text/html"
|
||
href="http://example.org/2005/04/02/atom"/>
|
||
<link rel="enclosure" type="audio/mpeg" length="1337"
|
||
href="http://example.org/audio/ph34r_my_podcast.mp3"/>
|
||
<id>tag:example.org,2003:3.2397</id>
|
||
<updated>2005-07-31T12:29:29Z</updated>
|
||
<published>2003-12-13T08:29:29-04:00</published>
|
||
<author>
|
||
<name>Mark Pilgrim</name>
|
||
<uri>http://example.org/</uri>
|
||
<email>f8dy@example.com</email>
|
||
</author>
|
||
<contributor>
|
||
<name>Sam Ruby</name>
|
||
</contributor>
|
||
<contributor>
|
||
<name>Joe Gregorio</name>
|
||
</contributor>
|
||
<content type="xhtml" xml:lang="en"
|
||
xml:base="http://diveintomark.org/">
|
||
<div xmlns="http://www.w3.org/1999/xhtml">
|
||
<p><i>[Update: The Atom draft is finished.]</i></p>
|
||
</div>
|
||
</content>
|
||
</entry>
|
||
</feed>
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 4]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-5"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h3"><a class="selflink" id="section-1.2" href="#section-1.2">1.2</a>. Namespace and Version</span>
|
||
|
||
The XML Namespaces URI [<a href="#ref-W3C.REC-xml-names-19990114">W3C.REC-xml-names-19990114</a>] for the XML data
|
||
format described in this specification is:
|
||
|
||
<a href="https://www.w3.org/2005/Atom">http://www.w3.org/2005/Atom</a>
|
||
|
||
For convenience, this data format may be referred to as "Atom 1.0".
|
||
This specification uses "Atom" internally.
|
||
|
||
<span class="h3"><a class="selflink" id="section-1.3" href="#section-1.3">1.3</a>. Notational Conventions</span>
|
||
|
||
This specification describes conformance in terms of two artifacts:
|
||
Atom Feed Documents and Atom Entry Documents. Additionally, it
|
||
places some requirements on Atom Processors.
|
||
|
||
This specification uses the namespace prefix "atom:" for the
|
||
Namespace URI identified in <a href="#section-1.2">Section 1.2</a>, above. Note that the choice
|
||
of namespace prefix is arbitrary and not semantically significant.
|
||
|
||
Atom is specified using terms from the XML Infoset
|
||
[<a href="#ref-W3C.REC-xml-infoset-20040204">W3C.REC-xml-infoset-20040204</a>]. However, this specification uses a
|
||
shorthand for two common terms: the phrase "Information Item" is
|
||
omitted when naming Element Information Items and Attribute
|
||
Information Items. Therefore, when this specification uses the term
|
||
"element," it is referring to an Element Information Item in Infoset
|
||
terms. Likewise, when it uses the term "attribute," it is referring
|
||
to an Attribute Information Item.
|
||
|
||
Some sections of this specification are illustrated with fragments of
|
||
a non-normative RELAX NG Compact schema [<a href="#ref-RELAX-NG" title=""RELAX NG Compact Syntax"">RELAX-NG</a>]. However, the
|
||
text of this specification provides the definition of conformance. A
|
||
complete schema appears in <a href="#appendix-B">Appendix B</a>.
|
||
|
||
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
|
||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
|
||
document are to be interpreted as described in <a data-savepage-href="/doc/html/bcp14" href="https://datatracker.ietf.org/doc/html/bcp14">BCP 14</a>, [<a data-savepage-href="/doc/html/rfc2119" href="https://datatracker.ietf.org/doc/html/rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>], as
|
||
scoped to those conformance targets.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 5]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-6"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Atom Documents</span>
|
||
|
||
This specification describes two kinds of Atom Documents: Atom Feed
|
||
Documents and Atom Entry Documents.
|
||
|
||
An Atom Feed Document is a representation of an Atom feed, including
|
||
metadata about the feed, and some or all of the entries associated
|
||
with it. Its root is the atom:feed element.
|
||
|
||
An Atom Entry Document represents exactly one Atom entry, outside of
|
||
the context of an Atom feed. Its root is the atom:entry element.
|
||
|
||
namespace atom = "http://www.w3.org/2005/Atom"
|
||
start = atomFeed | atomEntry
|
||
|
||
Both kinds of Atom Documents are specified in terms of the XML
|
||
Information Set, serialized as XML 1.0 [<a href="#ref-W3C.REC-xml-20040204">W3C.REC-xml-20040204</a>] and
|
||
identified with the "application/atom+xml" media type. Atom
|
||
Documents MUST be well-formed XML. This specification does not
|
||
define a DTD for Atom Documents, and hence does not require them to
|
||
be valid (in the sense used by XML).
|
||
|
||
Atom allows the use of IRIs [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>]. Every URI [<a data-savepage-href="/doc/html/rfc3986" href="https://datatracker.ietf.org/doc/html/rfc3986" title=""Uniform Resource Identifier (URI): Generic Syntax"">RFC3986</a>] is also
|
||
an IRI, so a URI may be used wherever below an IRI is named. There
|
||
are two special considerations: (1) when an IRI that is not also a
|
||
URI is given for dereferencing, it MUST be mapped to a URI using the
|
||
steps in <a data-savepage-href="/doc/html/rfc3987#section-3.1" href="https://datatracker.ietf.org/doc/html/rfc3987#section-3.1">Section 3.1 of [RFC3987]</a> and (2) when an IRI is serving as
|
||
an atom:id value, it MUST NOT be so mapped, so that the comparison
|
||
works as described in <a href="#section-4.2.6.1">Section 4.2.6.1</a>.
|
||
|
||
Any element defined by this specification MAY have an xml:base
|
||
attribute [<a href="#ref-W3C.REC-xmlbase-20010627">W3C.REC-xmlbase-20010627</a>]. When xml:base is used in an
|
||
Atom Document, it serves the function described in <a data-savepage-href="/doc/html/rfc3986#section-5.1.1" href="https://datatracker.ietf.org/doc/html/rfc3986#section-5.1.1">section 5.1.1 of
|
||
[RFC3986]</a>, establishing the base URI (or IRI) for resolving any
|
||
relative references found within the effective scope of the xml:base
|
||
attribute.
|
||
|
||
Any element defined by this specification MAY have an xml:lang
|
||
attribute, whose content indicates the natural language for the
|
||
element and its descendents. The language context is only
|
||
significant for elements and attributes declared to be "Language-
|
||
Sensitive" by this specification. Requirements regarding the content
|
||
and interpretation of xml:lang are specified in XML 1.0
|
||
[<a href="#ref-W3C.REC-xml-20040204">W3C.REC-xml-20040204</a>], Section 2.12.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 6]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-7"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
atomCommonAttributes =
|
||
attribute xml:base { atomUri }?,
|
||
attribute xml:lang { atomLanguageTag }?,
|
||
undefinedAttribute*
|
||
|
||
Atom is an extensible format. See <a href="#section-6">Section 6</a> of this document for a
|
||
full description of how Atom Documents can be extended.
|
||
|
||
Atom Processors MAY keep state sourced from Atom Feed Documents and
|
||
combine them with other Atom Feed Documents, in order to facilitate a
|
||
contiguous view of the contents of a feed. The manner in which Atom
|
||
Feed Documents are combined in order to reconstruct a feed (e.g.,
|
||
updating entries and metadata, dealing with missing entries) is out
|
||
of the scope of this specification.
|
||
|
||
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Common Atom Constructs</span>
|
||
|
||
Many of Atom's elements share a few common structures. This section
|
||
defines those structures and their requirements for convenient
|
||
reference by the appropriate element definitions.
|
||
|
||
When an element is identified as being a particular kind of
|
||
construct, it inherits the corresponding requirements from that
|
||
construct's definition in this section.
|
||
|
||
Note that there MUST NOT be any white space in a Date construct or in
|
||
any IRI. Some XML-emitting implementations erroneously insert white
|
||
space around values by default, and such implementations will emit
|
||
invalid Atom Documents.
|
||
|
||
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. Text Constructs</span>
|
||
|
||
A Text construct contains human-readable text, usually in small
|
||
quantities. The content of Text constructs is Language-Sensitive.
|
||
|
||
atomPlainTextConstruct =
|
||
atomCommonAttributes,
|
||
attribute type { "text" | "html" }?,
|
||
text
|
||
|
||
atomXHTMLTextConstruct =
|
||
atomCommonAttributes,
|
||
attribute type { "xhtml" },
|
||
xhtmlDiv
|
||
|
||
atomTextConstruct = atomPlainTextConstruct | atomXHTMLTextConstruct
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 7]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-8"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h4"><a class="selflink" id="section-3.1.1" href="#section-3.1.1">3.1.1</a>. The "type" Attribute</span>
|
||
|
||
Text constructs MAY have a "type" attribute. When present, the value
|
||
MUST be one of "text", "html", or "xhtml". If the "type" attribute
|
||
is not provided, Atom Processors MUST behave as though it were
|
||
present with a value of "text". Unlike the atom:content element
|
||
defined in <a href="#section-4.1.3">Section 4.1.3</a>, MIME media types [<a href="#ref-MIMEREG" title=""Media Type Specifications and Registration Procedures"">MIMEREG</a>] MUST NOT be used
|
||
as values for the "type" attribute on Text constructs.
|
||
|
||
<span class="h5"><a class="selflink" id="section-3.1.1.1" href="#section-3.1.1.1">3.1.1.1</a>. Text</span>
|
||
|
||
Example atom:title with text content:
|
||
|
||
...
|
||
<title type="text">
|
||
Less: &lt;
|
||
</title>
|
||
...
|
||
|
||
If the value is "text", the content of the Text construct MUST NOT
|
||
contain child elements. Such text is intended to be presented to
|
||
humans in a readable fashion. Thus, Atom Processors MAY collapse
|
||
white space (including line breaks) and display the text using
|
||
typographic techniques such as justification and proportional fonts.
|
||
|
||
<span class="h5"><a class="selflink" id="section-3.1.1.2" href="#section-3.1.1.2">3.1.1.2</a>. HTML</span>
|
||
|
||
Example atom:title with HTML content:
|
||
|
||
...
|
||
<title type="html">
|
||
Less: &lt;em> &amp;lt; &lt;/em>
|
||
</title>
|
||
...
|
||
|
||
If the value of "type" is "html", the content of the Text construct
|
||
MUST NOT contain child elements and SHOULD be suitable for handling
|
||
as HTML [<a href="#ref-HTML" title=""HTML 4.01 Specification"">HTML</a>]. Any markup within MUST be escaped; for example,
|
||
"<br>" as "&lt;br>". HTML markup within SHOULD be such that it could
|
||
validly appear directly within an HTML <DIV> element, after
|
||
unescaping. Atom Processors that display such content MAY use that
|
||
markup to aid in its display.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 8]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-9"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h5"><a class="selflink" id="section-3.1.1.3" href="#section-3.1.1.3">3.1.1.3</a>. XHTML</span>
|
||
|
||
Example atom:title with XHTML content:
|
||
|
||
...
|
||
<title type="xhtml" xmlns:xhtml="http://www.w3.org/1999/xhtml">
|
||
<xhtml:div>
|
||
Less: <xhtml:em> &lt; </xhtml:em>
|
||
</xhtml:div>
|
||
</title>
|
||
...
|
||
|
||
If the value of "type" is "xhtml", the content of the Text construct
|
||
MUST be a single XHTML div element [<a href="#ref-XHTML" title=""Modularization of XHTML[TM]"">XHTML</a>] and SHOULD be suitable for
|
||
handling as XHTML. The XHTML div element itself MUST NOT be
|
||
considered part of the content. Atom Processors that display the
|
||
content MAY use the markup to aid in displaying it. The escaped
|
||
versions of characters such as "&" and ">" represent those
|
||
characters, not markup.
|
||
|
||
|
||
Examples of valid XHTML content:
|
||
|
||
...
|
||
<summary type="xhtml">
|
||
<div xmlns="http://www.w3.org/1999/xhtml">
|
||
This is <b>XHTML</b> content.
|
||
</div>
|
||
</summary>
|
||
...
|
||
<summary type="xhtml">
|
||
<xhtml:div xmlns:xhtml="http://www.w3.org/1999/xhtml">
|
||
This is <xhtml:b>XHTML</xhtml:b> content.
|
||
</xhtml:div>
|
||
</summary>
|
||
...
|
||
|
||
The following example assumes that the XHTML namespace has been bound
|
||
to the "xh" prefix earlier in the document:
|
||
|
||
...
|
||
<summary type="xhtml">
|
||
<xh:div>
|
||
This is <xh:b>XHTML</xh:b> content.
|
||
</xh:div>
|
||
</summary>
|
||
...
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 9]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-10"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. Person Constructs</span>
|
||
|
||
A Person construct is an element that describes a person,
|
||
corporation, or similar entity (hereafter, 'person').
|
||
|
||
atomPersonConstruct =
|
||
atomCommonAttributes,
|
||
(element atom:name { text }
|
||
& element atom:uri { atomUri }?
|
||
& element atom:email { atomEmailAddress }?
|
||
& extensionElement*)
|
||
|
||
This specification assigns no significance to the order of appearance
|
||
of the child elements in a Person construct. Person constructs allow
|
||
extension Metadata elements (see <a href="#section-6.4">Section 6.4</a>).
|
||
|
||
<span class="h4"><a class="selflink" id="section-3.2.1" href="#section-3.2.1">3.2.1</a>. The "atom:name" Element</span>
|
||
|
||
The "atom:name" element's content conveys a human-readable name for
|
||
the person. The content of atom:name is Language-Sensitive. Person
|
||
constructs MUST contain exactly one "atom:name" element.
|
||
|
||
<span class="h4"><a class="selflink" id="section-3.2.2" href="#section-3.2.2">3.2.2</a>. The "atom:uri" Element</span>
|
||
|
||
The "atom:uri" element's content conveys an IRI associated with the
|
||
person. Person constructs MAY contain an atom:uri element, but MUST
|
||
NOT contain more than one. The content of atom:uri in a Person
|
||
construct MUST be an IRI reference [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>].
|
||
|
||
<span class="h4"><a class="selflink" id="section-3.2.3" href="#section-3.2.3">3.2.3</a>. The "atom:email" Element</span>
|
||
|
||
The "atom:email" element's content conveys an e-mail address
|
||
associated with the person. Person constructs MAY contain an
|
||
atom:email element, but MUST NOT contain more than one. Its content
|
||
MUST conform to the "addr-spec" production in [<a data-savepage-href="/doc/html/rfc2822" href="https://datatracker.ietf.org/doc/html/rfc2822" title=""Internet Message Format"">RFC2822</a>].
|
||
|
||
<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a>. Date Constructs</span>
|
||
|
||
A Date construct is an element whose content MUST conform to the
|
||
"date-time" production in [<a data-savepage-href="/doc/html/rfc3339" href="https://datatracker.ietf.org/doc/html/rfc3339" title=""Date and Time on the Internet: Timestamps"">RFC3339</a>]. In addition, an uppercase "T"
|
||
character MUST be used to separate date and time, and an uppercase
|
||
"Z" character MUST be present in the absence of a numeric time zone
|
||
offset.
|
||
|
||
atomDateConstruct =
|
||
atomCommonAttributes,
|
||
xsd:dateTime
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 10]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-11"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
Such date values happen to be compatible with the following
|
||
specifications: [<a href="#ref-ISO.8601.1988">ISO.8601.1988</a>], [<a href="#ref-W3C.NOTE-datetime-19980827">W3C.NOTE-datetime-19980827</a>], and
|
||
[<a href="#ref-W3C.REC-xmlschema-2-20041028">W3C.REC-xmlschema-2-20041028</a>].
|
||
|
||
Example Date constructs:
|
||
|
||
<updated>2003-12-13T18:30:02Z</updated>
|
||
<updated>2003-12-13T18:30:02.25Z</updated>
|
||
<updated>2003-12-13T18:30:02+01:00</updated>
|
||
<updated>2003-12-13T18:30:02.25+01:00</updated>
|
||
|
||
Date values SHOULD be as accurate as possible. For example, it would
|
||
be generally inappropriate for a publishing system to apply the same
|
||
timestamp to several entries that were published during the course of
|
||
a single day.
|
||
|
||
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Atom Element Definitions</span>
|
||
|
||
<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>. Container Elements</span>
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.1.1" href="#section-4.1.1">4.1.1</a>. The "atom:feed" Element</span>
|
||
|
||
The "atom:feed" element is the document (i.e., top-level) element of
|
||
an Atom Feed Document, acting as a container for metadata and data
|
||
associated with the feed. Its element children consist of metadata
|
||
elements followed by zero or more atom:entry child elements.
|
||
|
||
atomFeed =
|
||
element atom:feed {
|
||
atomCommonAttributes,
|
||
(atomAuthor*
|
||
& atomCategory*
|
||
& atomContributor*
|
||
& atomGenerator?
|
||
& atomIcon?
|
||
& atomId
|
||
& atomLink*
|
||
& atomLogo?
|
||
& atomRights?
|
||
& atomSubtitle?
|
||
& atomTitle
|
||
& atomUpdated
|
||
& extensionElement*),
|
||
atomEntry*
|
||
}
|
||
|
||
This specification assigns no significance to the order of atom:entry
|
||
elements within the feed.
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 11]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-12"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
The following child elements are defined by this specification (note
|
||
that the presence of some of these elements is required):
|
||
|
||
o atom:feed elements MUST contain one or more atom:author elements,
|
||
unless all of the atom:feed element's child atom:entry elements
|
||
contain at least one atom:author element.
|
||
o atom:feed elements MAY contain any number of atom:category
|
||
elements.
|
||
o atom:feed elements MAY contain any number of atom:contributor
|
||
elements.
|
||
o atom:feed elements MUST NOT contain more than one atom:generator
|
||
element.
|
||
o atom:feed elements MUST NOT contain more than one atom:icon
|
||
element.
|
||
o atom:feed elements MUST NOT contain more than one atom:logo
|
||
element.
|
||
o atom:feed elements MUST contain exactly one atom:id element.
|
||
o atom:feed elements SHOULD contain one atom:link element with a rel
|
||
attribute value of "self". This is the preferred URI for
|
||
retrieving Atom Feed Documents representing this Atom feed.
|
||
o atom:feed elements MUST NOT contain more than one atom:link
|
||
element with a rel attribute value of "alternate" that has the
|
||
same combination of type and hreflang attribute values.
|
||
o atom:feed elements MAY contain additional atom:link elements
|
||
beyond those described above.
|
||
o atom:feed elements MUST NOT contain more than one atom:rights
|
||
element.
|
||
o atom:feed elements MUST NOT contain more than one atom:subtitle
|
||
element.
|
||
o atom:feed elements MUST contain exactly one atom:title element.
|
||
o atom:feed elements MUST contain exactly one atom:updated element.
|
||
|
||
If multiple atom:entry elements with the same atom:id value appear in
|
||
an Atom Feed Document, they represent the same entry. Their
|
||
atom:updated timestamps SHOULD be different. If an Atom Feed
|
||
Document contains multiple entries with the same atom:id, Atom
|
||
Processors MAY choose to display all of them or some subset of them.
|
||
One typical behavior would be to display only the entry with the
|
||
latest atom:updated timestamp.
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.1.1.1" href="#section-4.1.1.1">4.1.1.1</a>. Providing Textual Content</span>
|
||
|
||
Experience teaches that feeds that contain textual content are in
|
||
general more useful than those that do not. Some applications (one
|
||
example is full-text indexers) require a minimum amount of text or
|
||
(X)HTML to function reliably and predictably. Feed producers should
|
||
be aware of these issues. It is advisable that each atom:entry
|
||
element contain a non-empty atom:title element, a non-empty
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 12]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-13"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
atom:content element when that element is present, and a non-empty
|
||
atom:summary element when the entry contains no atom:content element.
|
||
However, the absence of atom:summary is not an error, and Atom
|
||
Processors MUST NOT fail to function correctly as a consequence of
|
||
such an absence.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.1.2" href="#section-4.1.2">4.1.2</a>. The "atom:entry" Element</span>
|
||
|
||
The "atom:entry" element represents an individual entry, acting as a
|
||
container for metadata and data associated with the entry. This
|
||
element can appear as a child of the atom:feed element, or it can
|
||
appear as the document (i.e., top-level) element of a stand-alone
|
||
Atom Entry Document.
|
||
|
||
atomEntry =
|
||
element atom:entry {
|
||
atomCommonAttributes,
|
||
(atomAuthor*
|
||
& atomCategory*
|
||
& atomContent?
|
||
& atomContributor*
|
||
& atomId
|
||
& atomLink*
|
||
& atomPublished?
|
||
& atomRights?
|
||
& atomSource?
|
||
& atomSummary?
|
||
& atomTitle
|
||
& atomUpdated
|
||
& extensionElement*)
|
||
}
|
||
|
||
This specification assigns no significance to the order of appearance
|
||
of the child elements of atom:entry.
|
||
|
||
The following child elements are defined by this specification (note
|
||
that it requires the presence of some of these elements):
|
||
|
||
o atom:entry elements MUST contain one or more atom:author elements,
|
||
unless the atom:entry contains an atom:source element that
|
||
contains an atom:author element or, in an Atom Feed Document, the
|
||
atom:feed element contains an atom:author element itself.
|
||
o atom:entry elements MAY contain any number of atom:category
|
||
elements.
|
||
o atom:entry elements MUST NOT contain more than one atom:content
|
||
element.
|
||
o atom:entry elements MAY contain any number of atom:contributor
|
||
elements.
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 13]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-14"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
o atom:entry elements MUST contain exactly one atom:id element.
|
||
o atom:entry elements that contain no child atom:content element
|
||
MUST contain at least one atom:link element with a rel attribute
|
||
value of "alternate".
|
||
o atom:entry elements MUST NOT contain more than one atom:link
|
||
element with a rel attribute value of "alternate" that has the
|
||
same combination of type and hreflang attribute values.
|
||
o atom:entry elements MAY contain additional atom:link elements
|
||
beyond those described above.
|
||
o atom:entry elements MUST NOT contain more than one atom:published
|
||
element.
|
||
o atom:entry elements MUST NOT contain more than one atom:rights
|
||
element.
|
||
o atom:entry elements MUST NOT contain more than one atom:source
|
||
element.
|
||
o atom:entry elements MUST contain an atom:summary element in either
|
||
of the following cases:
|
||
* the atom:entry contains an atom:content that has a "src"
|
||
attribute (and is thus empty).
|
||
* the atom:entry contains content that is encoded in Base64;
|
||
i.e., the "type" attribute of atom:content is a MIME media type
|
||
[<a href="#ref-MIMEREG" title=""Media Type Specifications and Registration Procedures"">MIMEREG</a>], but is not an XML media type [<a data-savepage-href="/doc/html/rfc3023" href="https://datatracker.ietf.org/doc/html/rfc3023" title=""XML Media Types"">RFC3023</a>], does not
|
||
begin with "text/", and does not end with "/xml" or "+xml".
|
||
o atom:entry elements MUST NOT contain more than one atom:summary
|
||
element.
|
||
o atom:entry elements MUST contain exactly one atom:title element.
|
||
o atom:entry elements MUST contain exactly one atom:updated element.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.1.3" href="#section-4.1.3">4.1.3</a>. The "atom:content" Element</span>
|
||
|
||
The "atom:content" element either contains or links to the content of
|
||
the entry. The content of atom:content is Language-Sensitive.
|
||
|
||
atomInlineTextContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { "text" | "html" }?,
|
||
(text)*
|
||
}
|
||
|
||
atomInlineXHTMLContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { "xhtml" },
|
||
xhtmlDiv
|
||
}
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 14]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-15"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
atomInlineOtherContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { atomMediaType }?,
|
||
(text|anyElement)*
|
||
}
|
||
|
||
atomOutOfLineContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { atomMediaType }?,
|
||
attribute src { atomUri },
|
||
empty
|
||
}
|
||
|
||
atomContent = atomInlineTextContent
|
||
| atomInlineXHTMLContent
|
||
| atomInlineOtherContent
|
||
| atomOutOfLineContent
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.1.3.1" href="#section-4.1.3.1">4.1.3.1</a>. The "type" Attribute</span>
|
||
|
||
On the atom:content element, the value of the "type" attribute MAY be
|
||
one of "text", "html", or "xhtml". Failing that, it MUST conform to
|
||
the syntax of a MIME media type, but MUST NOT be a composite type
|
||
(see Section 4.2.6 of [<a href="#ref-MIMEREG" title=""Media Type Specifications and Registration Procedures"">MIMEREG</a>]). If neither the type attribute nor
|
||
the src attribute is provided, Atom Processors MUST behave as though
|
||
the type attribute were present with a value of "text".
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.1.3.2" href="#section-4.1.3.2">4.1.3.2</a>. The "src" Attribute</span>
|
||
|
||
atom:content MAY have a "src" attribute, whose value MUST be an IRI
|
||
reference [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>]. If the "src" attribute is present, atom:content
|
||
MUST be empty. Atom Processors MAY use the IRI to retrieve the
|
||
content and MAY choose to ignore remote content or to present it in a
|
||
different manner than local content.
|
||
|
||
If the "src" attribute is present, the "type" attribute SHOULD be
|
||
provided and MUST be a MIME media type [<a href="#ref-MIMEREG" title=""Media Type Specifications and Registration Procedures"">MIMEREG</a>], rather than "text",
|
||
"html", or "xhtml". The value is advisory; that is to say, when the
|
||
corresponding URI (mapped from an IRI, if necessary) is dereferenced,
|
||
if the server providing that content also provides a media type, the
|
||
server-provided media type is authoritative.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 15]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-16"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.1.3.3" href="#section-4.1.3.3">4.1.3.3</a>. Processing Model</span>
|
||
|
||
Atom Documents MUST conform to the following rules. Atom Processors
|
||
MUST interpret atom:content according to the first applicable rule.
|
||
|
||
1. If the value of "type" is "text", the content of atom:content
|
||
MUST NOT contain child elements. Such text is intended to be
|
||
presented to humans in a readable fashion. Thus, Atom Processors
|
||
MAY collapse white space (including line breaks), and display the
|
||
text using typographic techniques such as justification and
|
||
proportional fonts.
|
||
|
||
2. If the value of "type" is "html", the content of atom:content
|
||
MUST NOT contain child elements and SHOULD be suitable for
|
||
handling as HTML [<a href="#ref-HTML" title=""HTML 4.01 Specification"">HTML</a>]. The HTML markup MUST be escaped; for
|
||
example, "<br>" as "&lt;br>". The HTML markup SHOULD be such
|
||
that it could validly appear directly within an HTML <DIV>
|
||
element. Atom Processors that display the content MAY use the
|
||
markup to aid in displaying it.
|
||
|
||
3. If the value of "type" is "xhtml", the content of atom:content
|
||
MUST be a single XHTML div element [<a href="#ref-XHTML" title=""Modularization of XHTML[TM]"">XHTML</a>] and SHOULD be suitable
|
||
for handling as XHTML. The XHTML div element itself MUST NOT be
|
||
considered part of the content. Atom Processors that display the
|
||
content MAY use the markup to aid in displaying it. The escaped
|
||
versions of characters such as "&" and ">" represent those
|
||
characters, not markup.
|
||
|
||
4. If the value of "type" is an XML media type [<a data-savepage-href="/doc/html/rfc3023" href="https://datatracker.ietf.org/doc/html/rfc3023" title=""XML Media Types"">RFC3023</a>] or ends
|
||
with "+xml" or "/xml" (case insensitive), the content of
|
||
atom:content MAY include child elements and SHOULD be suitable
|
||
for handling as the indicated media type. If the "src" attribute
|
||
is not provided, this would normally mean that the "atom:content"
|
||
element would contain a single child element that would serve as
|
||
the root element of the XML document of the indicated type.
|
||
|
||
5. If the value of "type" begins with "text/" (case insensitive),
|
||
the content of atom:content MUST NOT contain child elements.
|
||
|
||
6. For all other values of "type", the content of atom:content MUST
|
||
be a valid Base64 encoding, as described in <a data-savepage-href="/doc/html/rfc3548#section-3" href="https://datatracker.ietf.org/doc/html/rfc3548#section-3">[RFC3548], section 3</a>.
|
||
When decoded, it SHOULD be suitable for handling as the indicated
|
||
media type. In this case, the characters in the Base64 encoding
|
||
MAY be preceded and followed in the atom:content element by white
|
||
space, and lines are separated by a single newline (U+000A)
|
||
character.
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 16]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-17"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.1.3.4" href="#section-4.1.3.4">4.1.3.4</a>. Examples</span>
|
||
|
||
XHTML inline:
|
||
|
||
...
|
||
<content type="xhtml">
|
||
<div xmlns="http://www.w3.org/1999/xhtml">
|
||
This is <b>XHTML</b> content.
|
||
</div>
|
||
</content>
|
||
...
|
||
<content type="xhtml">
|
||
<xhtml:div xmlns:xhtml="http://www.w3.org/1999/xhtml">
|
||
This is <xhtml:b>XHTML</xhtml:b> content.
|
||
</xhtml:div>
|
||
</content>
|
||
...
|
||
|
||
The following example assumes that the XHTML namespace has been bound
|
||
to the "xh" prefix earlier in the document:
|
||
|
||
...
|
||
<content type="xhtml">
|
||
<xh:div>
|
||
This is <xh:b>XHTML</xh:b> content.
|
||
</xh:div>
|
||
</content>
|
||
...
|
||
|
||
<span class="h3"><a class="selflink" id="section-4.2" href="#section-4.2">4.2</a>. Metadata Elements</span>
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.1" href="#section-4.2.1">4.2.1</a>. The "atom:author" Element</span>
|
||
|
||
The "atom:author" element is a Person construct that indicates the
|
||
author of the entry or feed.
|
||
|
||
atomAuthor = element atom:author { atomPersonConstruct }
|
||
|
||
If an atom:entry element does not contain atom:author elements, then
|
||
the atom:author elements of the contained atom:source element are
|
||
considered to apply. In an Atom Feed Document, the atom:author
|
||
elements of the containing atom:feed element are considered to apply
|
||
to the entry if there are no atom:author elements in the locations
|
||
described above.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 17]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-18"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.2" href="#section-4.2.2">4.2.2</a>. The "atom:category" Element</span>
|
||
|
||
The "atom:category" element conveys information about a category
|
||
associated with an entry or feed. This specification assigns no
|
||
meaning to the content (if any) of this element.
|
||
|
||
atomCategory =
|
||
element atom:category {
|
||
atomCommonAttributes,
|
||
attribute term { text },
|
||
attribute scheme { atomUri }?,
|
||
attribute label { text }?,
|
||
undefinedContent
|
||
}
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.2.1" href="#section-4.2.2.1">4.2.2.1</a>. The "term" Attribute</span>
|
||
|
||
The "term" attribute is a string that identifies the category to
|
||
which the entry or feed belongs. Category elements MUST have a
|
||
"term" attribute.
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.2.2" href="#section-4.2.2.2">4.2.2.2</a>. The "scheme" Attribute</span>
|
||
|
||
The "scheme" attribute is an IRI that identifies a categorization
|
||
scheme. Category elements MAY have a "scheme" attribute.
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.2.3" href="#section-4.2.2.3">4.2.2.3</a>. The "label" Attribute</span>
|
||
|
||
The "label" attribute provides a human-readable label for display in
|
||
end-user applications. The content of the "label" attribute is
|
||
Language-Sensitive. Entities such as "&amp;" and "&lt;" represent
|
||
their corresponding characters ("&" and "<", respectively), not
|
||
markup. Category elements MAY have a "label" attribute.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.3" href="#section-4.2.3">4.2.3</a>. The "atom:contributor" Element</span>
|
||
|
||
The "atom:contributor" element is a Person construct that indicates a
|
||
person or other entity who contributed to the entry or feed.
|
||
|
||
atomContributor = element atom:contributor { atomPersonConstruct }
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.4" href="#section-4.2.4">4.2.4</a>. The "atom:generator" Element</span>
|
||
|
||
The "atom:generator" element's content identifies the agent used to
|
||
generate a feed, for debugging and other purposes.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 18]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-19"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
atomGenerator = element atom:generator {
|
||
atomCommonAttributes,
|
||
attribute uri { atomUri }?,
|
||
attribute version { text }?,
|
||
text
|
||
}
|
||
|
||
The content of this element, when present, MUST be a string that is a
|
||
human-readable name for the generating agent. Entities such as
|
||
"&amp;" and "&lt;" represent their corresponding characters ("&" and
|
||
"<" respectively), not markup.
|
||
|
||
The atom:generator element MAY have a "uri" attribute whose value
|
||
MUST be an IRI reference [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>]. When dereferenced, the resulting
|
||
URI (mapped from an IRI, if necessary) SHOULD produce a
|
||
representation that is relevant to that agent.
|
||
|
||
The atom:generator element MAY have a "version" attribute that
|
||
indicates the version of the generating agent.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.5" href="#section-4.2.5">4.2.5</a>. The "atom:icon" Element</span>
|
||
|
||
The "atom:icon" element's content is an IRI reference [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>] that
|
||
identifies an image that provides iconic visual identification for a
|
||
feed.
|
||
|
||
atomIcon = element atom:icon {
|
||
atomCommonAttributes,
|
||
(atomUri)
|
||
}
|
||
|
||
The image SHOULD have an aspect ratio of one (horizontal) to one
|
||
(vertical) and SHOULD be suitable for presentation at a small size.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.6" href="#section-4.2.6">4.2.6</a>. The "atom:id" Element</span>
|
||
|
||
The "atom:id" element conveys a permanent, universally unique
|
||
identifier for an entry or feed.
|
||
|
||
atomId = element atom:id {
|
||
atomCommonAttributes,
|
||
(atomUri)
|
||
}
|
||
|
||
Its content MUST be an IRI, as defined by [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>]. Note that the
|
||
definition of "IRI" excludes relative references. Though the IRI
|
||
might use a dereferencable scheme, Atom Processors MUST NOT assume it
|
||
can be dereferenced.
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 19]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-20"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
When an Atom Document is relocated, migrated, syndicated,
|
||
republished, exported, or imported, the content of its atom:id
|
||
element MUST NOT change. Put another way, an atom:id element
|
||
pertains to all instantiations of a particular Atom entry or feed;
|
||
revisions retain the same content in their atom:id elements. It is
|
||
suggested that the atom:id element be stored along with the
|
||
associated resource.
|
||
|
||
The content of an atom:id element MUST be created in a way that
|
||
assures uniqueness.
|
||
|
||
Because of the risk of confusion between IRIs that would be
|
||
equivalent if they were mapped to URIs and dereferenced, the
|
||
following normalization strategy SHOULD be applied when generating
|
||
atom:id elements:
|
||
|
||
o Provide the scheme in lowercase characters.
|
||
o Provide the host, if any, in lowercase characters.
|
||
o Only perform percent-encoding where it is essential.
|
||
o Use uppercase A through F characters when percent-encoding.
|
||
o Prevent dot-segments from appearing in paths.
|
||
o For schemes that define a default authority, use an empty
|
||
authority if the default is desired.
|
||
o For schemes that define an empty path to be equivalent to a path
|
||
of "/", use "/".
|
||
o For schemes that define a port, use an empty port if the default
|
||
is desired.
|
||
o Preserve empty fragment identifiers and queries.
|
||
o Ensure that all components of the IRI are appropriately character
|
||
normalized, e.g., by using NFC or NFKC.
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.6.1" href="#section-4.2.6.1">4.2.6.1</a>. Comparing atom:id</span>
|
||
|
||
Instances of atom:id elements can be compared to determine whether an
|
||
entry or feed is the same as one seen before. Processors MUST
|
||
compare atom:id elements on a character-by-character basis (in a
|
||
case-sensitive fashion). Comparison operations MUST be based solely
|
||
on the IRI character strings and MUST NOT rely on dereferencing the
|
||
IRIs or URIs mapped from them.
|
||
|
||
As a result, two IRIs that resolve to the same resource but are not
|
||
character-for-character identical will be considered different for
|
||
the purposes of identifier comparison.
|
||
|
||
For example, these are four distinct identifiers, despite the fact
|
||
that they differ only in case:
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 20]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-21"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
http://www.example.org/thing
|
||
http://www.example.org/Thing
|
||
http://www.EXAMPLE.org/thing
|
||
HTTP://www.example.org/thing
|
||
|
||
Likewise, these are three distinct identifiers, because IRI
|
||
%-escaping is significant for the purposes of comparison:
|
||
|
||
http://www.example.com/~bob
|
||
http://www.example.com/%7ebob
|
||
http://www.example.com/%7Ebob
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.7" href="#section-4.2.7">4.2.7</a>. The "atom:link" Element</span>
|
||
|
||
The "atom:link" element defines a reference from an entry or feed to
|
||
a Web resource. This specification assigns no meaning to the content
|
||
(if any) of this element.
|
||
|
||
atomLink =
|
||
element atom:link {
|
||
atomCommonAttributes,
|
||
attribute href { atomUri },
|
||
attribute rel { atomNCName | atomUri }?,
|
||
attribute type { atomMediaType }?,
|
||
attribute hreflang { atomLanguageTag }?,
|
||
attribute title { text }?,
|
||
attribute length { text }?,
|
||
undefinedContent
|
||
}
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.7.1" href="#section-4.2.7.1">4.2.7.1</a>. The "href" Attribute</span>
|
||
|
||
The "href" attribute contains the link's IRI. atom:link elements MUST
|
||
have an href attribute, whose value MUST be a IRI reference
|
||
[<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>].
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.7.2" href="#section-4.2.7.2">4.2.7.2</a>. The "rel" Attribute</span>
|
||
|
||
atom:link elements MAY have a "rel" attribute that indicates the link
|
||
relation type. If the "rel" attribute is not present, the link
|
||
element MUST be interpreted as if the link relation type is
|
||
"alternate".
|
||
|
||
The value of "rel" MUST be a string that is non-empty and matches
|
||
either the "isegment-nz-nc" or the "IRI" production in [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>].
|
||
Note that use of a relative reference other than a simple name is not
|
||
allowed. If a name is given, implementations MUST consider the link
|
||
relation type equivalent to the same name registered within the IANA
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 21]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-22"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
Registry of Link Relations (<a href="#section-7">Section 7</a>), and thus to the IRI that
|
||
would be obtained by appending the value of the rel attribute to the
|
||
string "http://www.iana.org/assignments/relation/". The value of
|
||
"rel" describes the meaning of the link, but does not impose any
|
||
behavioral requirements on Atom Processors.
|
||
|
||
This document defines five initial values for the Registry of Link
|
||
Relations:
|
||
|
||
1. The value "alternate" signifies that the IRI in the value of the
|
||
href attribute identifies an alternate version of the resource
|
||
described by the containing element.
|
||
|
||
2. The value "related" signifies that the IRI in the value of the
|
||
href attribute identifies a resource related to the resource
|
||
described by the containing element. For example, the feed for a
|
||
site that discusses the performance of the search engine at
|
||
"http://search.example.com" might contain, as a child of
|
||
atom:feed:
|
||
|
||
<link rel="related" href="http://search.example.com/"/>
|
||
|
||
An identical link might appear as a child of any atom:entry whose
|
||
content contains a discussion of that same search engine.
|
||
|
||
3. The value "self" signifies that the IRI in the value of the href
|
||
attribute identifies a resource equivalent to the containing
|
||
element.
|
||
|
||
4. The value "enclosure" signifies that the IRI in the value of the
|
||
href attribute identifies a related resource that is potentially
|
||
large in size and might require special handling. For atom:link
|
||
elements with rel="enclosure", the length attribute SHOULD be
|
||
provided.
|
||
|
||
5. The value "via" signifies that the IRI in the value of the href
|
||
attribute identifies a resource that is the source of the
|
||
information provided in the containing element.
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.7.3" href="#section-4.2.7.3">4.2.7.3</a>. The "type" Attribute</span>
|
||
|
||
On the link element, the "type" attribute's value is an advisory
|
||
media type: it is a hint about the type of the representation that is
|
||
expected to be returned when the value of the href attribute is
|
||
dereferenced. Note that the type attribute does not override the
|
||
actual media type returned with the representation. Link elements
|
||
MAY have a type attribute, whose value MUST conform to the syntax of
|
||
a MIME media type [<a href="#ref-MIMEREG" title=""Media Type Specifications and Registration Procedures"">MIMEREG</a>].
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 22]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-23"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.7.4" href="#section-4.2.7.4">4.2.7.4</a>. The "hreflang" Attribute</span>
|
||
|
||
The "hreflang" attribute's content describes the language of the
|
||
resource pointed to by the href attribute. When used together with
|
||
the rel="alternate", it implies a translated version of the entry.
|
||
Link elements MAY have an hreflang attribute, whose value MUST be a
|
||
language tag [<a data-savepage-href="/doc/html/rfc3066" href="https://datatracker.ietf.org/doc/html/rfc3066" title=""Tags for the Identification of Languages"">RFC3066</a>].
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.7.5" href="#section-4.2.7.5">4.2.7.5</a>. The "title" Attribute</span>
|
||
|
||
The "title" attribute conveys human-readable information about the
|
||
link. The content of the "title" attribute is Language-Sensitive.
|
||
Entities such as "&amp;" and "&lt;" represent their corresponding
|
||
characters ("&" and "<", respectively), not markup. Link elements
|
||
MAY have a title attribute.
|
||
|
||
<span class="h5"><a class="selflink" id="section-4.2.7.6" href="#section-4.2.7.6">4.2.7.6</a>. The "length" Attribute</span>
|
||
|
||
The "length" attribute indicates an advisory length of the linked
|
||
content in octets; it is a hint about the content length of the
|
||
representation returned when the IRI in the href attribute is mapped
|
||
to a URI and dereferenced. Note that the length attribute does not
|
||
override the actual content length of the representation as reported
|
||
by the underlying protocol. Link elements MAY have a length
|
||
attribute.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.8" href="#section-4.2.8">4.2.8</a>. The "atom:logo" Element</span>
|
||
|
||
The "atom:logo" element's content is an IRI reference [<a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987" title=""Internationalized Resource Identifiers (IRIs)"">RFC3987</a>] that
|
||
identifies an image that provides visual identification for a feed.
|
||
|
||
atomLogo = element atom:logo {
|
||
atomCommonAttributes,
|
||
(atomUri)
|
||
}
|
||
|
||
The image SHOULD have an aspect ratio of 2 (horizontal) to 1
|
||
(vertical).
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.9" href="#section-4.2.9">4.2.9</a>. The "atom:published" Element</span>
|
||
|
||
The "atom:published" element is a Date construct indicating an
|
||
instant in time associated with an event early in the life cycle of
|
||
the entry.
|
||
|
||
atomPublished = element atom:published { atomDateConstruct }
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 23]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-24"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
Typically, atom:published will be associated with the initial
|
||
creation or first availability of the resource.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.10" href="#section-4.2.10">4.2.10</a>. The "atom:rights" Element</span>
|
||
|
||
The "atom:rights" element is a Text construct that conveys
|
||
information about rights held in and over an entry or feed.
|
||
|
||
atomRights = element atom:rights { atomTextConstruct }
|
||
|
||
The atom:rights element SHOULD NOT be used to convey machine-readable
|
||
licensing information.
|
||
|
||
If an atom:entry element does not contain an atom:rights element,
|
||
then the atom:rights element of the containing atom:feed element, if
|
||
present, is considered to apply to the entry.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.11" href="#section-4.2.11">4.2.11</a>. The "atom:source" Element</span>
|
||
|
||
If an atom:entry is copied from one feed into another feed, then the
|
||
source atom:feed's metadata (all child elements of atom:feed other
|
||
than the atom:entry elements) MAY be preserved within the copied
|
||
entry by adding an atom:source child element, if it is not already
|
||
present in the entry, and including some or all of the source feed's
|
||
Metadata elements as the atom:source element's children. Such
|
||
metadata SHOULD be preserved if the source atom:feed contains any of
|
||
the child elements atom:author, atom:contributor, atom:rights, or
|
||
atom:category and those child elements are not present in the source
|
||
atom:entry.
|
||
|
||
atomSource =
|
||
element atom:source {
|
||
atomCommonAttributes,
|
||
(atomAuthor*
|
||
& atomCategory*
|
||
& atomContributor*
|
||
& atomGenerator?
|
||
& atomIcon?
|
||
& atomId?
|
||
& atomLink*
|
||
& atomLogo?
|
||
& atomRights?
|
||
& atomSubtitle?
|
||
& atomTitle?
|
||
& atomUpdated?
|
||
& extensionElement*)
|
||
}
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 24]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-25"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
The atom:source element is designed to allow the aggregation of
|
||
entries from different feeds while retaining information about an
|
||
entry's source feed. For this reason, Atom Processors that are
|
||
performing such aggregation SHOULD include at least the required
|
||
feed-level Metadata elements (atom:id, atom:title, and atom:updated)
|
||
in the atom:source element.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.12" href="#section-4.2.12">4.2.12</a>. The "atom:subtitle" Element</span>
|
||
|
||
The "atom:subtitle" element is a Text construct that conveys a human-
|
||
readable description or subtitle for a feed.
|
||
|
||
atomSubtitle = element atom:subtitle { atomTextConstruct }
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.13" href="#section-4.2.13">4.2.13</a>. The "atom:summary" Element</span>
|
||
|
||
The "atom:summary" element is a Text construct that conveys a short
|
||
summary, abstract, or excerpt of an entry.
|
||
|
||
atomSummary = element atom:summary { atomTextConstruct }
|
||
|
||
It is not advisable for the atom:summary element to duplicate
|
||
atom:title or atom:content because Atom Processors might assume there
|
||
is a useful summary when there is none.
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.14" href="#section-4.2.14">4.2.14</a>. The "atom:title" Element</span>
|
||
|
||
The "atom:title" element is a Text construct that conveys a human-
|
||
readable title for an entry or feed.
|
||
|
||
atomTitle = element atom:title { atomTextConstruct }
|
||
|
||
<span class="h4"><a class="selflink" id="section-4.2.15" href="#section-4.2.15">4.2.15</a>. The "atom:updated" Element</span>
|
||
|
||
The "atom:updated" element is a Date construct indicating the most
|
||
recent instant in time when an entry or feed was modified in a way
|
||
the publisher considers significant. Therefore, not all
|
||
modifications necessarily result in a changed atom:updated value.
|
||
|
||
atomUpdated = element atom:updated { atomDateConstruct }
|
||
|
||
Publishers MAY change the value of this element over time.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 25]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-26"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Securing Atom Documents</span>
|
||
|
||
Because Atom is an XML-based format, existing XML security mechanisms
|
||
can be used to secure its content.
|
||
|
||
Producers of feeds and/or entries, and intermediaries who aggregate
|
||
feeds and/or entries, may have sound reasons for signing and/or
|
||
encrypting otherwise-unprotected content. For example, a merchant
|
||
might digitally sign a message that contains a discount coupon for
|
||
its products. A bank that uses Atom to deliver customer statements
|
||
is very likely to want to sign and encrypt those messages to protect
|
||
their customers' financial information and to assure the customer of
|
||
their authenticity. Intermediaries may want to encrypt aggregated
|
||
feeds so that a passive observer cannot tell what topics the
|
||
recipient is interested in. Of course, many other examples exist as
|
||
well.
|
||
|
||
The algorithm requirements in this section pertain to the Atom
|
||
Processor. They require that a recipient, at a minimum, be able to
|
||
handle messages that use the specified cryptographic algorithms.
|
||
These requirements do not limit the algorithms that the sender can
|
||
choose.
|
||
|
||
<span class="h3"><a class="selflink" id="section-5.1" href="#section-5.1">5.1</a>. Digital Signatures</span>
|
||
|
||
The root of an Atom Document (i.e., atom:feed in an Atom Feed
|
||
Document, atom:entry in an Atom Entry Document) or any atom:entry
|
||
element MAY have an Enveloped Signature, as described by XML-
|
||
Signature and Syntax Processing [<a href="#ref-W3C.REC-xmldsig-core-20020212">W3C.REC-xmldsig-core-20020212</a>].
|
||
|
||
Atom Processors MUST NOT reject an Atom Document containing such a
|
||
signature because they are not capable of verifying it; they MUST
|
||
continue processing and MAY inform the user of their failure to
|
||
validate the signature.
|
||
|
||
In other words, the presence of an element with the namespace URI
|
||
"http://www.w3.org/2000/09/xmldsig#" and a local name of "Signature"
|
||
as a child of the document element MUST NOT cause an Atom Processor
|
||
to fail merely because of its presence.
|
||
|
||
Other elements in an Atom Document MUST NOT be signed unless their
|
||
definitions explicitly specify such a capability.
|
||
|
||
Section 6.5.1 of [<a href="#ref-W3C.REC-xmldsig-core-20020212">W3C.REC-xmldsig-core-20020212</a>] requires support for
|
||
Canonical XML [<a href="#ref-W3C.REC-xml-c14n-20010315">W3C.REC-xml-c14n-20010315</a>]. However, many
|
||
implementers do not use it because signed XML documents enclosed in
|
||
other XML documents have their signatures broken. Thus, Atom
|
||
Processors that verify signed Atom Documents MUST be able to
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 26]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-27"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
canonicalize with the exclusive XML canonicalization method
|
||
identified by the URI "http://www.w3.org/2001/10/xml-exc-c14n#", as
|
||
specified in Exclusive XML Canonicalization
|
||
[<a href="#ref-W3C.REC-xml-exc-c14n-20020718">W3C.REC-xml-exc-c14n-20020718</a>].
|
||
|
||
Intermediaries such as aggregators may need to add an atom:source
|
||
element to an entry that does not contain its own atom:source
|
||
element. If such an entry is signed, the addition will break the
|
||
signature. Thus, a publisher of individually-signed entries should
|
||
strongly consider adding an atom:source element to those entries
|
||
before signing them. Implementers should also be aware of the issues
|
||
concerning the use of markup in the "xml:" namespace as it interacts
|
||
with canonicalization.
|
||
|
||
Section 4.4.2 of [<a href="#ref-W3C.REC-xmldsig-core-20020212">W3C.REC-xmldsig-core-20020212</a>] requires support for
|
||
DSA signatures and recommends support for RSA signatures. However,
|
||
because of the much greater popularity in the market of RSA versus
|
||
DSA, Atom Processors that verify signed Atom Documents MUST be able
|
||
to verify RSA signatures, but do not need be able to verify DSA
|
||
signatures. Due to security issues that can arise if the keying
|
||
material for message authentication code (MAC) authentication is not
|
||
handled properly, Atom Documents SHOULD NOT use MACs for signatures.
|
||
|
||
<span class="h3"><a class="selflink" id="section-5.2" href="#section-5.2">5.2</a>. Encryption</span>
|
||
|
||
The root of an Atom Document (i.e., atom:feed in an Atom Feed
|
||
Document, atom:entry in an Atom Entry Document) MAY be encrypted,
|
||
using the mechanisms described by XML Encryption Syntax and
|
||
Processing [<a href="#ref-W3C.REC-xmlenc-core-20021210">W3C.REC-xmlenc-core-20021210</a>].
|
||
|
||
Section 5.1 of [<a href="#ref-W3C.REC-xmlenc-core-20021210">W3C.REC-xmlenc-core-20021210</a>] requires support of
|
||
TripleDES, AES-128, and AES-256. Atom Processors that decrypt Atom
|
||
Documents MUST be able to decrypt with AES-128 in Cipher Block
|
||
Chaining (CBC) mode.
|
||
|
||
Encryption based on [<a href="#ref-W3C.REC-xmlenc-core-20021210">W3C.REC-xmlenc-core-20021210</a>] does not ensure
|
||
integrity of the original document. There are known cryptographic
|
||
attacks where someone who cannot decrypt a message can still change
|
||
bits in a way where part or all the decrypted message makes sense but
|
||
has a different meaning. Thus, Atom Processors that decrypt Atom
|
||
Documents SHOULD check the integrity of the decrypted document by
|
||
verifying the hash in the signature (if any) in the document, or by
|
||
verifying a hash of the document within the document (if any).
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 27]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-28"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h3"><a class="selflink" id="section-5.3" href="#section-5.3">5.3</a>. Signing and Encrypting</span>
|
||
|
||
When an Atom Document is to be both signed and encrypted, it is
|
||
generally a good idea to first sign the document, then encrypt the
|
||
signed document. This provides integrity to the base document while
|
||
encrypting all the information, including the identity of the entity
|
||
that signed the document. Note that, if MACs are used for
|
||
authentication, the order MUST be that the document is signed and
|
||
then encrypted, and not the other way around.
|
||
|
||
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. Extending Atom</span>
|
||
|
||
<span class="h3"><a class="selflink" id="section-6.1" href="#section-6.1">6.1</a>. Extensions from Non-Atom Vocabularies</span>
|
||
|
||
This specification describes Atom's XML markup vocabulary. Markup
|
||
from other vocabularies ("foreign markup") can be used in an Atom
|
||
Document. Note that the atom:content element is designed to support
|
||
the inclusion of arbitrary foreign markup.
|
||
|
||
<span class="h3"><a class="selflink" id="section-6.2" href="#section-6.2">6.2</a>. Extensions to the Atom Vocabulary</span>
|
||
|
||
The Atom namespace is reserved for future forward-compatible
|
||
revisions of Atom. Future versions of this specification could add
|
||
new elements and attributes to the Atom markup vocabulary. Software
|
||
written to conform to this version of the specification will not be
|
||
able to process such markup correctly and, in fact, will not be able
|
||
to distinguish it from markup error. For the purposes of this
|
||
discussion, unrecognized markup from the Atom vocabulary will be
|
||
considered "foreign markup".
|
||
|
||
<span class="h3"><a class="selflink" id="section-6.3" href="#section-6.3">6.3</a>. Processing Foreign Markup</span>
|
||
|
||
Atom Processors that encounter foreign markup in a location that is
|
||
legal according to this specification MUST NOT stop processing or
|
||
signal an error. It might be the case that the Atom Processor is
|
||
able to process the foreign markup correctly and does so. Otherwise,
|
||
such markup is termed "unknown foreign markup".
|
||
|
||
When unknown foreign markup is encountered as a child of atom:entry,
|
||
atom:feed, or a Person construct, Atom Processors MAY bypass the
|
||
markup and any textual content and MUST NOT change their behavior as
|
||
a result of the markup's presence.
|
||
|
||
When unknown foreign markup is encountered in a Text Construct or
|
||
atom:content element, software SHOULD ignore the markup and process
|
||
any text content of foreign elements as though the surrounding markup
|
||
were not present.
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 28]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-29"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h3"><a class="selflink" id="section-6.4" href="#section-6.4">6.4</a>. Extension Elements</span>
|
||
|
||
Atom allows foreign markup anywhere in an Atom document, except where
|
||
it is explicitly forbidden. Child elements of atom:entry, atom:feed,
|
||
atom:source, and Person constructs are considered Metadata elements
|
||
and are described below. Child elements of Person constructs are
|
||
considered to apply to the construct. The role of other foreign
|
||
markup is undefined by this specification.
|
||
|
||
<span class="h4"><a class="selflink" id="section-6.4.1" href="#section-6.4.1">6.4.1</a>. Simple Extension Elements</span>
|
||
|
||
A Simple Extension element MUST NOT have any attributes or child
|
||
elements. The element MAY contain character data or be empty.
|
||
Simple Extension elements are not Language-Sensitive.
|
||
|
||
simpleExtensionElement =
|
||
element * - atom:* {
|
||
text
|
||
}
|
||
|
||
The element can be interpreted as a simple property (or name/value
|
||
pair) of the parent element that encloses it. The pair consisting of
|
||
the namespace-URI of the element and the local name of the element
|
||
can be interpreted as the name of the property. The character data
|
||
content of the element can be interpreted as the value of the
|
||
property. If the element is empty, then the property value can be
|
||
interpreted as an empty string.
|
||
|
||
<span class="h4"><a class="selflink" id="section-6.4.2" href="#section-6.4.2">6.4.2</a>. Structured Extension Elements</span>
|
||
|
||
The root element of a Structured Extension element MUST have at least
|
||
one attribute or child element. It MAY have attributes, it MAY
|
||
contain well-formed XML content (including character data), or it MAY
|
||
be empty. Structured Extension elements are Language-Sensitive.
|
||
|
||
structuredExtensionElement =
|
||
element * - atom:* {
|
||
(attribute * { text }+,
|
||
(text|anyElement)*)
|
||
| (attribute * { text }*,
|
||
(text?, anyElement+, (text|anyElement)*))
|
||
}
|
||
|
||
The structure of a Structured Extension element, including the order
|
||
of its child elements, could be significant.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 29]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-30"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
This specification does not provide an interpretation of a Structured
|
||
Extension element. The syntax of the XML contained in the element
|
||
(and an interpretation of how the element relates to its containing
|
||
element) is defined by the specification of the Atom extension.
|
||
|
||
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. IANA Considerations</span>
|
||
|
||
An Atom Document, when serialized as XML 1.0, can be identified with
|
||
the following media type:
|
||
|
||
MIME media type name: application
|
||
MIME subtype name: atom+xml
|
||
Mandatory parameters: None.
|
||
Optional parameters:
|
||
"charset": This parameter has semantics identical to the charset
|
||
parameter of the "application/xml" media type as specified in
|
||
[<a data-savepage-href="/doc/html/rfc3023" href="https://datatracker.ietf.org/doc/html/rfc3023" title=""XML Media Types"">RFC3023</a>].
|
||
Encoding considerations: Identical to those of "application/xml" as
|
||
described in <a data-savepage-href="/doc/html/rfc3023#section-3.2" href="https://datatracker.ietf.org/doc/html/rfc3023#section-3.2">[RFC3023], Section 3.2</a>.
|
||
Security considerations: As defined in this specification.
|
||
In addition, as this media type uses the "+xml" convention, it
|
||
shares the same security considerations as described in <a data-savepage-href="/doc/html/rfc3023#section-10" href="https://datatracker.ietf.org/doc/html/rfc3023#section-10">[RFC3023],
|
||
Section 10</a>.
|
||
Interoperability considerations: There are no known interoperability
|
||
issues.
|
||
Published specification: This specification.
|
||
Applications that use this media type: No known applications
|
||
currently use this media type.
|
||
|
||
Additional information:
|
||
|
||
Magic number(s): As specified for "application/xml" in <a data-savepage-href="/doc/html/rfc3023#section-3.2" href="https://datatracker.ietf.org/doc/html/rfc3023#section-3.2">[RFC3023],
|
||
Section 3.2</a>.
|
||
File extension: .atom
|
||
Fragment identifiers: As specified for "application/xml" in
|
||
<a data-savepage-href="/doc/html/rfc3023#section-5" href="https://datatracker.ietf.org/doc/html/rfc3023#section-5">[RFC3023], Section 5</a>.
|
||
Base URI: As specified in <a data-savepage-href="/doc/html/rfc3023#section-6" href="https://datatracker.ietf.org/doc/html/rfc3023#section-6">[RFC3023], Section 6</a>.
|
||
Macintosh File Type code: TEXT
|
||
Person and email address to contact for further information: Mark
|
||
Nottingham <mnot@pobox.com>
|
||
Intended usage: COMMON
|
||
Author/Change controller: IESG
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 30]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-31"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h3"><a class="selflink" id="section-7.1" href="#section-7.1">7.1</a>. Registry of Link Relations</span>
|
||
|
||
This registry is maintained by IANA and initially contains five
|
||
values: "alternate", "related", "self", "enclosure", and "via". New
|
||
assignments are subject to IESG Approval, as outlined in [<a data-savepage-href="/doc/html/rfc2434" href="https://datatracker.ietf.org/doc/html/rfc2434" title="">RFC2434</a>].
|
||
Requests should be made by email to IANA, which will then forward the
|
||
request to the IESG, requesting approval. The request should use the
|
||
following template:
|
||
|
||
o Attribute Value: (A value for the "rel" attribute that conforms to
|
||
the syntax rule given in <a href="#section-4.2.7.2">Section 4.2.7.2</a>)
|
||
o Description:
|
||
o Expected display characteristics:
|
||
o Security considerations:
|
||
|
||
<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. Security Considerations</span>
|
||
|
||
<span class="h3"><a class="selflink" id="section-8.1" href="#section-8.1">8.1</a>. HTML and XHTML Content</span>
|
||
|
||
Text constructs and atom:content allow the delivery of HTML and
|
||
XHTML. Many elements in these languages are considered 'unsafe' in
|
||
that they open clients to one or more types of attack. Implementers
|
||
of software that processes Atom should carefully consider their
|
||
handling of every type of element when processing incoming (X)HTML in
|
||
Atom Documents. See the security sections of [<a data-savepage-href="/doc/html/rfc2854" href="https://datatracker.ietf.org/doc/html/rfc2854" title=""The 'text/html' Media Type"">RFC2854</a>] and [<a href="#ref-HTML" title=""HTML 4.01 Specification"">HTML</a>]
|
||
for guidance.
|
||
|
||
Atom Processors should pay particular attention to the security of
|
||
the IMG, SCRIPT, EMBED, OBJECT, FRAME, FRAMESET, IFRAME, META, and
|
||
LINK elements, but other elements might also have negative security
|
||
properties.
|
||
|
||
(X)HTML can either directly contain or indirectly reference
|
||
executable content.
|
||
|
||
<span class="h3"><a class="selflink" id="section-8.2" href="#section-8.2">8.2</a>. URIs</span>
|
||
|
||
Atom Processors handle URIs. See <a data-savepage-href="/doc/html/rfc3986#section-7" href="https://datatracker.ietf.org/doc/html/rfc3986#section-7">Section 7 of [RFC3986]</a>.
|
||
|
||
<span class="h3"><a class="selflink" id="section-8.3" href="#section-8.3">8.3</a>. IRIs</span>
|
||
|
||
Atom Processors handle IRIs. See <a data-savepage-href="/doc/html/rfc3987#section-8" href="https://datatracker.ietf.org/doc/html/rfc3987#section-8">Section 8 of [RFC3987]</a>.
|
||
|
||
<span class="h3"><a class="selflink" id="section-8.4" href="#section-8.4">8.4</a>. Spoofing</span>
|
||
|
||
Atom Processors should be aware of the potential for spoofing attacks
|
||
where the attacker publishes an atom:entry with the atom:id value of
|
||
an entry from another feed, perhaps with a falsified atom:source
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 31]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-32"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
element duplicating the atom:id of the other feed. For example, an
|
||
Atom Processor could suppress display of duplicate entries by
|
||
displaying only one entry from a set of entries with identical
|
||
atom:id values. In that situation, the Atom Processor might also
|
||
take steps to determine whether the entries originated from the same
|
||
publisher before considering them duplicates.
|
||
|
||
<span class="h3"><a class="selflink" id="section-8.5" href="#section-8.5">8.5</a>. Encryption and Signing</span>
|
||
|
||
Atom Documents can be encrypted and signed using
|
||
[<a href="#ref-W3C.REC-xmlenc-core-20021210">W3C.REC-xmlenc-core-20021210</a>] and [<a href="#ref-W3C.REC-xmldsig-core-20020212">W3C.REC-xmldsig-core-20020212</a>],
|
||
respectively, and are subject to the security considerations implied
|
||
by their use.
|
||
|
||
Digital signatures provide authentication, message integrity, and
|
||
non-repudiation with proof of origin. Encryption provides data
|
||
confidentiality.
|
||
|
||
<span class="h2"><a class="selflink" id="section-9" href="#section-9">9</a>. References</span>
|
||
|
||
<span class="h3"><a class="selflink" id="section-9.1" href="#section-9.1">9.1</a>. Normative References</span>
|
||
|
||
[<a id="ref-HTML">HTML</a>] Raggett, D., Hors, A., and I. Jacobs, "HTML 4.01
|
||
Specification", W3C REC REC-html401-19991224,
|
||
December 1999,
|
||
<<a href="https://www.w3.org/TR/1999/REC-html401-19991224">http://www.w3.org/TR/1999/REC-html401-19991224</a>>.
|
||
|
||
[<a id="ref-MIMEREG">MIMEREG</a>] Freed, N. and J. Klensin, "Media Type Specifications and
|
||
Registration Procedures", <a data-savepage-href="/doc/html/bcp13" href="https://datatracker.ietf.org/doc/html/bcp13">BCP 13</a>, <a data-savepage-href="/doc/html/rfc4288" href="https://datatracker.ietf.org/doc/html/rfc4288">RFC 4288</a>, December 2005.
|
||
|
||
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
|
||
Requirement Levels", <a data-savepage-href="/doc/html/bcp14" href="https://datatracker.ietf.org/doc/html/bcp14">BCP 14</a>, <a data-savepage-href="/doc/html/rfc2119" href="https://datatracker.ietf.org/doc/html/rfc2119">RFC 2119</a>, March 1997.
|
||
|
||
[<a id="ref-RFC2822">RFC2822</a>] Resnick, P., "Internet Message Format", <a data-savepage-href="/doc/html/rfc2822" href="https://datatracker.ietf.org/doc/html/rfc2822">RFC 2822</a>,
|
||
April 2001.
|
||
|
||
[<a id="ref-RFC2854">RFC2854</a>] Connolly, D. and L. Masinter, "The 'text/html' Media
|
||
Type", <a data-savepage-href="/doc/html/rfc2854" href="https://datatracker.ietf.org/doc/html/rfc2854">RFC 2854</a>, June 2000.
|
||
|
||
[<a id="ref-RFC3023">RFC3023</a>] Murata, M., St. Laurent, S., and D. Kohn, "XML Media
|
||
Types", <a data-savepage-href="/doc/html/rfc3023" href="https://datatracker.ietf.org/doc/html/rfc3023">RFC 3023</a>, January 2001.
|
||
|
||
[<a id="ref-RFC3066">RFC3066</a>] Alvestrand, H., "Tags for the Identification of
|
||
Languages", <a data-savepage-href="/doc/html/bcp47" href="https://datatracker.ietf.org/doc/html/bcp47">BCP 47</a>, <a data-savepage-href="/doc/html/rfc3066" href="https://datatracker.ietf.org/doc/html/rfc3066">RFC 3066</a>, January 2001.
|
||
|
||
[<a id="ref-RFC3339">RFC3339</a>] Klyne, G. and C. Newman, "Date and Time on the Internet:
|
||
Timestamps", <a data-savepage-href="/doc/html/rfc3339" href="https://datatracker.ietf.org/doc/html/rfc3339">RFC 3339</a>, July 2002.
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 32]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-33"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
[<a id="ref-RFC3548">RFC3548</a>] Josefsson, S., "The Base16, Base32, and Base64 Data
|
||
Encodings", <a data-savepage-href="/doc/html/rfc3548" href="https://datatracker.ietf.org/doc/html/rfc3548">RFC 3548</a>, July 2003.
|
||
|
||
[<a id="ref-RFC3986">RFC3986</a>] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
|
||
Resource Identifier (URI): Generic Syntax", STD 66,
|
||
<a data-savepage-href="/doc/html/rfc3986" href="https://datatracker.ietf.org/doc/html/rfc3986">RFC 3986</a>, January 2005.
|
||
|
||
[<a id="ref-RFC3987">RFC3987</a>] Duerst, M. and M. Suignard, "Internationalized Resource
|
||
Identifiers (IRIs)", <a data-savepage-href="/doc/html/rfc3987" href="https://datatracker.ietf.org/doc/html/rfc3987">RFC 3987</a>, January 2005.
|
||
|
||
[<a id="ref-W3C.REC-xml-20040204">W3C.REC-xml-20040204</a>]
|
||
Yergeau, F., Paoli, J., Sperberg-McQueen, C., Bray, T.,
|
||
and E. Maler, "Extensible Markup Language (XML) 1.0 (Third
|
||
Edition)", W3C REC REC-xml-20040204, February 2004,
|
||
<<a href="https://www.w3.org/TR/2004/REC-xml-20040204">http://www.w3.org/TR/2004/REC-xml-20040204</a>>.
|
||
|
||
[<a id="ref-W3C.REC-xml-c14n-20010315">W3C.REC-xml-c14n-20010315</a>]
|
||
Boyer, J., "Canonical XML Version 1.0", W3C REC REC-xml-
|
||
c14n-20010315, March 2001,
|
||
<<a href="https://www.w3.org/TR/2001/REC-xml-c14n-20010315">http://www.w3.org/TR/2001/REC-xml-c14n-20010315</a>>.
|
||
|
||
[<a id="ref-W3C.REC-xml-exc-c14n-20020718">W3C.REC-xml-exc-c14n-20020718</a>]
|
||
Eastlake, D., Boyer, J., and J. Reagle, "Exclusive XML
|
||
Canonicalization Version 1.0", W3C REC REC-xml-exc-c14n-
|
||
20020718, July 2002,
|
||
<<a href="https://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718">http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718</a>>.
|
||
|
||
[<a id="ref-W3C.REC-xml-infoset-20040204">W3C.REC-xml-infoset-20040204</a>]
|
||
Cowan, J. and R. Tobin, "XML Information Set (Second
|
||
Edition)", W3C REC REC-xml-infoset-20040204,
|
||
February 2004,
|
||
<<a href="https://www.w3.org/TR/2004/REC-xml-infoset-20040204">http://www.w3.org/TR/2004/REC-xml-infoset-20040204</a>>.
|
||
|
||
[<a id="ref-W3C.REC-xml-names-19990114">W3C.REC-xml-names-19990114</a>]
|
||
Hollander, D., Bray, T., and A. Layman, "Namespaces in
|
||
XML", W3C REC REC-xml-names-19990114, January 1999,
|
||
<<a href="https://www.w3.org/TR/1999/REC-xml-names-19990114">http://www.w3.org/TR/1999/REC-xml-names-19990114</a>>.
|
||
|
||
[<a id="ref-W3C.REC-xmlbase-20010627">W3C.REC-xmlbase-20010627</a>]
|
||
Marsh, J., "XML Base", W3C REC REC-xmlbase-20010627,
|
||
June 2001,
|
||
<<a href="https://www.w3.org/TR/2001/REC-xmlbase-20010627">http://www.w3.org/TR/2001/REC-xmlbase-20010627</a>>.
|
||
|
||
[<a id="ref-W3C.REC-xmldsig-core-20020212">W3C.REC-xmldsig-core-20020212</a>]
|
||
Solo, D., Reagle, J., and D. Eastlake, "XML-Signature
|
||
Syntax and Processing", W3C REC REC-xmldsig-core-20020212,
|
||
February 2002,
|
||
<<a href="https://www.w3.org/TR/2002/REC-xmldsig-core-20020212">http://www.w3.org/TR/2002/REC-xmldsig-core-20020212</a>>.
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 33]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-34"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
[<a id="ref-W3C.REC-xmlenc-core-20021210">W3C.REC-xmlenc-core-20021210</a>]
|
||
Reagle, J. and D. Eastlake, "XML Encryption Syntax and
|
||
Processing", W3C REC REC-xmlenc-core-20021210,
|
||
December 2002,
|
||
<<a href="https://www.w3.org/TR/2002/REC-xmlenc-core-20021210">http://www.w3.org/TR/2002/REC-xmlenc-core-20021210</a>>.
|
||
|
||
[<a id="ref-XHTML">XHTML</a>] Altheim, M., Boumphrey, F., McCarron, S., Dooley, S.,
|
||
Schnitzenbaumer, S., and T. Wugofski, "Modularization of
|
||
XHTML[TM]", W3C REC REC-xhtml-modularization-20010410,
|
||
April 2001, <<a href="https://www.w3.org/TR/2001/REC-xhtml-modularization-20010410">http://www.w3.org/TR/2001/</a>
|
||
<a href="https://www.w3.org/TR/2001/REC-xhtml-modularization-20010410">REC-xhtml-modularization-20010410</a>>.
|
||
|
||
<span class="h3"><a class="selflink" id="section-9.2" href="#section-9.2">9.2</a>. Informative References</span>
|
||
|
||
[<a id="ref-ISO.8601.1988">ISO.8601.1988</a>]
|
||
International Organization for Standardization, "Data
|
||
elements and interchange formats - Information interchange
|
||
- Representation of dates and times", ISO Standard 8601,
|
||
June 1988.
|
||
|
||
[<a id="ref-RELAX-NG">RELAX-NG</a>] Clark, J., "RELAX NG Compact Syntax", December 2001,
|
||
<<a href="http://www.oasis-open.org/committees/relax-ng/compact-20021121.html">http://www.oasis-open.org/committees/relax-ng/</a>
|
||
<a href="http://www.oasis-open.org/committees/relax-ng/compact-20021121.html">compact-20021121.html</a>>.
|
||
|
||
[<a id="ref-RFC2434">RFC2434</a>] Narten, T. and H. Alvestrand, "Guidelines for Writing an
|
||
IANA Considerations Section in RFCs", <a data-savepage-href="/doc/html/bcp26" href="https://datatracker.ietf.org/doc/html/bcp26">BCP 26</a>, <a data-savepage-href="/doc/html/rfc2434" href="https://datatracker.ietf.org/doc/html/rfc2434">RFC 2434</a>,
|
||
October 1998.
|
||
|
||
[<a id="ref-W3C.NOTE-datetime-19980827">W3C.NOTE-datetime-19980827</a>]
|
||
Wolf, M. and C. Wicksteed, "Date and Time Formats", W3C
|
||
NOTE NOTE-datetime-19980827, August 1998,
|
||
<<a href="https://www.w3.org/TR/1998/NOTE-datetime-19980827">http://www.w3.org/TR/1998/NOTE-datetime-19980827</a>>.
|
||
|
||
[<a id="ref-W3C.REC-xmlschema-2-20041028">W3C.REC-xmlschema-2-20041028</a>]
|
||
Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes
|
||
Second Edition", W3C REC REC-xmlschema-2-20041028,
|
||
October 2004,
|
||
<<a href="https://www.w3.org/TR/2004/REC-xmlschema-2-20041028">http://www.w3.org/TR/2004/REC-xmlschema-2-20041028</a>>.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 34]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-35"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
<span class="h2"><a class="selflink" id="appendix-A" href="#appendix-A">Appendix A</a>. Contributors</span>
|
||
|
||
The following people contributed to preliminary versions of this
|
||
document: Tim Bray, Mark Pilgrim, and Sam Ruby. Norman Walsh
|
||
provided the Relax NG schema. The content and concepts within are a
|
||
product of the Atom community and the Atompub Working Group.
|
||
|
||
The Atompub Working Group has dozens of very active contributors who
|
||
proposed ideas and wording for this document, including:
|
||
|
||
Danny Ayers, James Aylett, Roger Benningfield, Arve Bersvendsen, Tim
|
||
Bray, Dan Brickley, Thomas Broyer, Robin Cover, Bill de hOra, Martin
|
||
Duerst, Roy Fielding, Joe Gregorio, Bjoern Hoehrmann, Paul Hoffman,
|
||
Anne van Kesteren, Brett Lindsley, Dare Obasanjo, David Orchard,
|
||
Aristotle Pagaltzis, John Panzer, Graham Parks, Dave Pawson, Mark
|
||
Pilgrim, David Powell, Julian Reschke, Phil Ringnalda, Antone Roundy,
|
||
Sam Ruby, Eric Scheid, Brent Simmons, Henri Sivonen, Ray Slakinski,
|
||
James Snell, Henry Story, Asbjorn Ulsberg, Walter Underwood, Norman
|
||
Walsh, Dave Winer, and Bob Wyman.
|
||
|
||
<span class="h2"><a class="selflink" id="appendix-B" href="#appendix-B">Appendix B</a>. RELAX NG Compact Schema</span>
|
||
|
||
This appendix is informative.
|
||
|
||
The Relax NG schema explicitly excludes elements in the Atom
|
||
namespace that are not defined in this revision of the specification.
|
||
Requirements for Atom Processors encountering such markup are given
|
||
in Sections <a href="#section-6.2">6.2</a> and <a href="#section-6.3">6.3</a>.
|
||
|
||
# -*- rnc -*-
|
||
# RELAX NG Compact Syntax Grammar for the
|
||
# Atom Format Specification Version 11
|
||
|
||
namespace atom = "http://www.w3.org/2005/Atom"
|
||
namespace xhtml = "http://www.w3.org/1999/xhtml"
|
||
namespace s = "http://www.ascc.net/xml/schematron"
|
||
namespace local = ""
|
||
|
||
start = atomFeed | atomEntry
|
||
|
||
# Common attributes
|
||
|
||
atomCommonAttributes =
|
||
attribute xml:base { atomUri }?,
|
||
attribute xml:lang { atomLanguageTag }?,
|
||
undefinedAttribute*
|
||
|
||
# Text Constructs
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 35]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-36"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
atomPlainTextConstruct =
|
||
atomCommonAttributes,
|
||
attribute type { "text" | "html" }?,
|
||
text
|
||
|
||
atomXHTMLTextConstruct =
|
||
atomCommonAttributes,
|
||
attribute type { "xhtml" },
|
||
xhtmlDiv
|
||
|
||
atomTextConstruct = atomPlainTextConstruct | atomXHTMLTextConstruct
|
||
|
||
# Person Construct
|
||
|
||
atomPersonConstruct =
|
||
atomCommonAttributes,
|
||
(element atom:name { text }
|
||
& element atom:uri { atomUri }?
|
||
& element atom:email { atomEmailAddress }?
|
||
& extensionElement*)
|
||
|
||
# Date Construct
|
||
|
||
atomDateConstruct =
|
||
atomCommonAttributes,
|
||
xsd:dateTime
|
||
|
||
# atom:feed
|
||
|
||
atomFeed =
|
||
[
|
||
s:rule [
|
||
context = "atom:feed"
|
||
s:assert [
|
||
test = "atom:author or not(atom:entry[not(atom:author)])"
|
||
"An atom:feed must have an atom:author unless all "
|
||
~ "of its atom:entry children have an atom:author."
|
||
]
|
||
]
|
||
]
|
||
element atom:feed {
|
||
atomCommonAttributes,
|
||
(atomAuthor*
|
||
& atomCategory*
|
||
& atomContributor*
|
||
& atomGenerator?
|
||
& atomIcon?
|
||
& atomId
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 36]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-37"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
& atomLink*
|
||
& atomLogo?
|
||
& atomRights?
|
||
& atomSubtitle?
|
||
& atomTitle
|
||
& atomUpdated
|
||
& extensionElement*),
|
||
atomEntry*
|
||
}
|
||
|
||
# atom:entry
|
||
|
||
atomEntry =
|
||
[
|
||
s:rule [
|
||
context = "atom:entry"
|
||
s:assert [
|
||
test = "atom:link[@rel='alternate'] "
|
||
~ "or atom:link[not(@rel)] "
|
||
~ "or atom:content"
|
||
"An atom:entry must have at least one atom:link element "
|
||
~ "with a rel attribute of 'alternate' "
|
||
~ "or an atom:content."
|
||
]
|
||
]
|
||
s:rule [
|
||
context = "atom:entry"
|
||
s:assert [
|
||
test = "atom:author or "
|
||
~ "../atom:author or atom:source/atom:author"
|
||
"An atom:entry must have an atom:author "
|
||
~ "if its feed does not."
|
||
]
|
||
]
|
||
]
|
||
element atom:entry {
|
||
atomCommonAttributes,
|
||
(atomAuthor*
|
||
& atomCategory*
|
||
& atomContent?
|
||
& atomContributor*
|
||
& atomId
|
||
& atomLink*
|
||
& atomPublished?
|
||
& atomRights?
|
||
& atomSource?
|
||
& atomSummary?
|
||
& atomTitle
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 37]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-38"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
& atomUpdated
|
||
& extensionElement*)
|
||
}
|
||
|
||
# atom:content
|
||
|
||
atomInlineTextContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { "text" | "html" }?,
|
||
(text)*
|
||
}
|
||
|
||
atomInlineXHTMLContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { "xhtml" },
|
||
xhtmlDiv
|
||
}
|
||
|
||
atomInlineOtherContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { atomMediaType }?,
|
||
(text|anyElement)*
|
||
}
|
||
|
||
atomOutOfLineContent =
|
||
element atom:content {
|
||
atomCommonAttributes,
|
||
attribute type { atomMediaType }?,
|
||
attribute src { atomUri },
|
||
empty
|
||
}
|
||
|
||
atomContent = atomInlineTextContent
|
||
| atomInlineXHTMLContent
|
||
| atomInlineOtherContent
|
||
| atomOutOfLineContent
|
||
|
||
# atom:author
|
||
|
||
atomAuthor = element atom:author { atomPersonConstruct }
|
||
|
||
# atom:category
|
||
|
||
atomCategory =
|
||
element atom:category {
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 38]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-39"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
atomCommonAttributes,
|
||
attribute term { text },
|
||
attribute scheme { atomUri }?,
|
||
attribute label { text }?,
|
||
undefinedContent
|
||
}
|
||
|
||
# atom:contributor
|
||
|
||
atomContributor = element atom:contributor { atomPersonConstruct }
|
||
|
||
# atom:generator
|
||
|
||
atomGenerator = element atom:generator {
|
||
atomCommonAttributes,
|
||
attribute uri { atomUri }?,
|
||
attribute version { text }?,
|
||
text
|
||
}
|
||
|
||
# atom:icon
|
||
|
||
atomIcon = element atom:icon {
|
||
atomCommonAttributes,
|
||
(atomUri)
|
||
}
|
||
|
||
# atom:id
|
||
|
||
atomId = element atom:id {
|
||
atomCommonAttributes,
|
||
(atomUri)
|
||
}
|
||
|
||
# atom:logo
|
||
|
||
atomLogo = element atom:logo {
|
||
atomCommonAttributes,
|
||
(atomUri)
|
||
}
|
||
|
||
# atom:link
|
||
|
||
atomLink =
|
||
element atom:link {
|
||
atomCommonAttributes,
|
||
attribute href { atomUri },
|
||
attribute rel { atomNCName | atomUri }?,
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 39]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-40"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
attribute type { atomMediaType }?,
|
||
attribute hreflang { atomLanguageTag }?,
|
||
attribute title { text }?,
|
||
attribute length { text }?,
|
||
undefinedContent
|
||
}
|
||
|
||
# atom:published
|
||
|
||
atomPublished = element atom:published { atomDateConstruct }
|
||
|
||
# atom:rights
|
||
|
||
atomRights = element atom:rights { atomTextConstruct }
|
||
|
||
# atom:source
|
||
|
||
atomSource =
|
||
element atom:source {
|
||
atomCommonAttributes,
|
||
(atomAuthor*
|
||
& atomCategory*
|
||
& atomContributor*
|
||
& atomGenerator?
|
||
& atomIcon?
|
||
& atomId?
|
||
& atomLink*
|
||
& atomLogo?
|
||
& atomRights?
|
||
& atomSubtitle?
|
||
& atomTitle?
|
||
& atomUpdated?
|
||
& extensionElement*)
|
||
}
|
||
|
||
# atom:subtitle
|
||
|
||
atomSubtitle = element atom:subtitle { atomTextConstruct }
|
||
|
||
# atom:summary
|
||
|
||
atomSummary = element atom:summary { atomTextConstruct }
|
||
|
||
# atom:title
|
||
|
||
atomTitle = element atom:title { atomTextConstruct }
|
||
|
||
# atom:updated
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 40]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-41"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
atomUpdated = element atom:updated { atomDateConstruct }
|
||
|
||
# Low-level simple types
|
||
|
||
atomNCName = xsd:string { minLength = "1" pattern = "[^:]*" }
|
||
|
||
# Whatever a media type is, it contains at least one slash
|
||
atomMediaType = xsd:string { pattern = ".+/.+" }
|
||
|
||
# As defined in <a data-savepage-href="/doc/html/rfc3066" href="https://datatracker.ietf.org/doc/html/rfc3066">RFC 3066</a>
|
||
atomLanguageTag = xsd:string {
|
||
pattern = "[A-Za-z]{1,8}(-[A-Za-z0-9]{1,8})*"
|
||
}
|
||
|
||
# Unconstrained; it's not entirely clear how IRI fit into
|
||
# xsd:anyURI so let's not try to constrain it here
|
||
atomUri = text
|
||
|
||
# Whatever an email address is, it contains at least one @
|
||
atomEmailAddress = xsd:string { pattern = ".+@.+" }
|
||
|
||
# Simple Extension
|
||
|
||
simpleExtensionElement =
|
||
element * - atom:* {
|
||
text
|
||
}
|
||
|
||
# Structured Extension
|
||
|
||
structuredExtensionElement =
|
||
element * - atom:* {
|
||
(attribute * { text }+,
|
||
(text|anyElement)*)
|
||
| (attribute * { text }*,
|
||
(text?, anyElement+, (text|anyElement)*))
|
||
}
|
||
|
||
# Other Extensibility
|
||
|
||
extensionElement =
|
||
simpleExtensionElement | structuredExtensionElement
|
||
|
||
undefinedAttribute =
|
||
attribute * - (xml:base | xml:lang | local:*) { text }
|
||
|
||
undefinedContent = (text|anyForeignElement)*
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 41]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-42"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
anyElement =
|
||
element * {
|
||
(attribute * { text }
|
||
| text
|
||
| anyElement)*
|
||
}
|
||
|
||
anyForeignElement =
|
||
element * - atom:* {
|
||
(attribute * { text }
|
||
| text
|
||
| anyElement)*
|
||
}
|
||
|
||
# XHTML
|
||
|
||
anyXHTML = element xhtml:* {
|
||
(attribute * { text }
|
||
| text
|
||
| anyXHTML)*
|
||
}
|
||
|
||
xhtmlDiv = element xhtml:div {
|
||
(attribute * { text }
|
||
| text
|
||
| anyXHTML)*
|
||
}
|
||
|
||
# EOF
|
||
|
||
Authors' Addresses
|
||
|
||
Mark Nottingham (editor)
|
||
|
||
EMail: mnot@pobox.com
|
||
URI: <a href="https://www.mnot.net/">http://www.mnot.net/</a>
|
||
|
||
|
||
Robert Sayre (editor)
|
||
|
||
EMail: rfsayre@boswijck.com
|
||
URI: <a data-savepage-href="http://boswijck.com" href="http://boswijck.com/">http://boswijck.com</a>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<span class="grey">Nottingham & Sayre Standards Track [Page 42]</span></pre>
|
||
<hr class="noprint"><!--NewPage--><pre class="newpage"><span id="page-43"></span>
|
||
<span class="grey"><a data-savepage-href="/doc/html/rfc4287" href="https://datatracker.ietf.org/doc/html/rfc4287">RFC 4287</a> Atom Format December 2005</span>
|
||
|
||
|
||
Full Copyright Statement
|
||
|
||
Copyright (C) The Internet Society (2005).
|
||
|
||
This document is subject to the rights, licenses and restrictions
|
||
contained in <a data-savepage-href="/doc/html/bcp78" href="https://datatracker.ietf.org/doc/html/bcp78">BCP 78</a>, and except as set forth therein, the authors
|
||
retain all their rights.
|
||
|
||
This document and the information contained herein are provided on an
|
||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
||
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
||
ENGINEERING TASK FORCE DISCLAIM 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.
|
||
|
||
Intellectual Property
|
||
|
||
The IETF takes no position regarding the validity or scope of any
|
||
Intellectual Property Rights 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; nor does it represent that it has
|
||
made any independent effort to identify any such rights. Information
|
||
on the procedures with respect to rights in RFC documents can be
|
||
found in <a data-savepage-href="/doc/html/bcp78" href="https://datatracker.ietf.org/doc/html/bcp78">BCP 78</a> and <a data-savepage-href="/doc/html/bcp79" href="https://datatracker.ietf.org/doc/html/bcp79">BCP 79</a>.
|
||
|
||
Copies of IPR disclosures made to the IETF Secretariat 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 on-line IPR repository at
|
||
<a href="https://www.ietf.org/ipr">http://www.ietf.org/ipr</a>.
|
||
|
||
The IETF invites any interested party to bring to its attention any
|
||
copyrights, patents or patent applications, or other proprietary
|
||
rights that may cover technology that may be required to implement
|
||
this standard. Please address the information to the IETF at ietf-
|
||
ipr@ietf.org.
|
||
|
||
Acknowledgement
|
||
|
||
Funding for the RFC Editor function is currently provided by the
|
||
Internet Society.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
Nottingham & Sayre Standards Track [Page 43]
|
||
</pre>
|
||
</div>
|
||
|
||
</div>
|
||
|
||
|
||
|
||
</div>
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
<script type="text/javascript"></script>
|
||
|
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|
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