draft-ietf-atompub-format-02.txt   draft-ietf-atompub-format-03.txt 
Network Working Group M. Nottingham, Ed. Network Working Group M. Nottingham, Ed.
Internet-Draft
Expires: March 6, 2005 Expires: April 20, 2005 R. Sayre, Ed.
Boswijck Memex Consulting
October 20, 2004
The Atom Syndication Format The Atom Syndication Format
draft-ietf-atompub-format-02 draft-ietf-atompub-format-03
Status of this Memo Status of this Memo
By submitting this Internet-Draft, I certify that any applicable By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed, patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance with and any of which I become aware will be disclosed, in accordance with
RFC 3668. RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 33 skipping to change at page 1, line 34
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This Internet-Draft will expire on March 6, 2005. This Internet-Draft will expire on April 20, 2005.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract Abstract
This document specifies Atom, an XML-based Web content and metadata This document specifies Atom, an XML-based Web content and metadata
syndication format. syndication format.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Editorial Notes . . . . . . . . . . . . . . . . . . . . . 4 1.1 Editorial Notes . . . . . . . . . . . . . . . . . . . . . 4
1.2 Example . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Example . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Conformance . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Conformance . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Notational Conventions . . . . . . . . . . . . . . . . . . 5 1.4 Notational Conventions . . . . . . . . . . . . . . . . . . 5
2. Atom Documents . . . . . . . . . . . . . . . . . . . . . . . 7 2. Atom Documents . . . . . . . . . . . . . . . . . . . . . . . 7
3. Common Atom Constructs . . . . . . . . . . . . . . . . . . . 9 3. Common Atom Constructs . . . . . . . . . . . . . . . . . . . 8
3.1 Content Constructs . . . . . . . . . . . . . . . . . . . . 9 3.1 Text Constructs . . . . . . . . . . . . . . . . . . . . . 8
3.1.1 "type" Attribute . . . . . . . . . . . . . . . . . . . 9 3.1.1 "type" Attribute . . . . . . . . . . . . . . . . . . . 8
3.1.2 "mode" Attribute . . . . . . . . . . . . . . . . . . . 9 3.2 Person Constructs . . . . . . . . . . . . . . . . . . . . 8
3.2 Person Constructs . . . . . . . . . . . . . . . . . . . . 9 3.2.1 "atom:name" Element . . . . . . . . . . . . . . . . . 9
3.2.1 "atom:name" Element . . . . . . . . . . . . . . . . . 10 3.2.2 "atom:uri" Element . . . . . . . . . . . . . . . . . . 9
3.2.2 "atom:uri" Element . . . . . . . . . . . . . . . . . . 10 3.2.3 "atom:email" Element . . . . . . . . . . . . . . . . . 9
3.2.3 "atom:email" Element . . . . . . . . . . . . . . . . . 10 3.3 Date Constructs . . . . . . . . . . . . . . . . . . . . . 9
3.3 Date Constructs . . . . . . . . . . . . . . . . . . . . . 10 3.4 Service Constructs . . . . . . . . . . . . . . . . . . . . 9
3.4 Link Constructs . . . . . . . . . . . . . . . . . . . . . 10 3.4.1 "href" Attribute . . . . . . . . . . . . . . . . . . . 9
3.4.1 "rel" Attribute . . . . . . . . . . . . . . . . . . . 10 3.5 Link Constructs . . . . . . . . . . . . . . . . . . . . . 10
3.4.2 "type" Attribute . . . . . . . . . . . . . . . . . . . 11 3.5.1 "rel" Attribute . . . . . . . . . . . . . . . . . . . 10
3.4.3 "href" Attribute . . . . . . . . . . . . . . . . . . . 11 3.5.2 "type" Attribute . . . . . . . . . . . . . . . . . . . 10
3.4.4 "hreflang" Attribute . . . . . . . . . . . . . . . . . 11 3.5.3 "href" Attribute . . . . . . . . . . . . . . . . . . . 10
3.4.5 "title" Attribute . . . . . . . . . . . . . . . . . . 11 3.5.4 "hreflang" Attribute . . . . . . . . . . . . . . . . . 10
3.5 Identity Constructs . . . . . . . . . . . . . . . . . . . 11 3.5.5 "title" Attribute . . . . . . . . . . . . . . . . . . 11
3.5.1 Dereferencing Identity Constructs . . . . . . . . . . 11 3.6 Identity Constructs . . . . . . . . . . . . . . . . . . . 11
3.5.2 Comparing Identity Constructs . . . . . . . . . . . . 12 3.6.1 Dereferencing Identity Constructs . . . . . . . . . . 11
3.6.2 Comparing Identity Constructs . . . . . . . . . . . . 12
4. The "atom:feed" Element . . . . . . . . . . . . . . . . . . 13 4. The "atom:feed" Element . . . . . . . . . . . . . . . . . . 13
4.1 "version" Attribute . . . . . . . . . . . . . . . . . . . 13 4.1 "version" Attribute . . . . . . . . . . . . . . . . . . . 13
4.2 The "atom:head" Element . . . . . . . . . . . . . . . . . 13 4.2 The "atom:head" Element . . . . . . . . . . . . . . . . . 13
4.2.1 "atom:title" Element . . . . . . . . . . . . . . . . . 13 4.2.1 "atom:title" Element . . . . . . . . . . . . . . . . . 13
4.2.2 "atom:link" Element . . . . . . . . . . . . . . . . . 13 4.2.2 "atom:link" Element . . . . . . . . . . . . . . . . . 13
4.2.3 "atom:author" Element . . . . . . . . . . . . . . . . 14 4.2.3 "atom:introspection" Element . . . . . . . . . . . . . 14
4.2.4 "atom:contributor" Element . . . . . . . . . . . . . . 14 4.2.4 "atom:post" Element . . . . . . . . . . . . . . . . . 14
4.2.5 "atom:tagline" Element . . . . . . . . . . . . . . . . 14 4.2.5 "atom:author" Element . . . . . . . . . . . . . . . . 14
4.2.6 "atom:id" Element . . . . . . . . . . . . . . . . . . 14 4.2.6 "atom:contributor" Element . . . . . . . . . . . . . . 14
4.2.7 "atom:generator" Element . . . . . . . . . . . . . . . 14 4.2.7 "atom:tagline" Element . . . . . . . . . . . . . . . . 14
4.2.8 "atom:copyright" Element . . . . . . . . . . . . . . . 15 4.2.8 "atom:id" Element . . . . . . . . . . . . . . . . . . 14
4.2.9 "atom:info" Element . . . . . . . . . . . . . . . . . 15 4.2.9 "atom:generator" Element . . . . . . . . . . . . . . . 15
4.2.10 "atom:modified" Element . . . . . . . . . . . . . . 15 4.2.10 "atom:copyright" Element . . . . . . . . . . . . . . 15
5. The "atom:entry" Element . . . . . . . . . . . . . . . . . . 16 4.2.11 "atom:info" Element . . . . . . . . . . . . . . . . 15
5.1 "atom:title" Element . . . . . . . . . . . . . . . . . . . 16 4.2.12 "atom:updated" Element . . . . . . . . . . . . . . . 16
5.2 "atom:link" Element . . . . . . . . . . . . . . . . . . . 16 5. The "atom:entry" Element . . . . . . . . . . . . . . . . . . 17
5.3 "atom:author" Element . . . . . . . . . . . . . . . . . . 16 5.1 "atom:title" Element . . . . . . . . . . . . . . . . . . . 17
5.4 "atom:contributor" Element . . . . . . . . . . . . . . . . 17 5.2 "atom:link" Element . . . . . . . . . . . . . . . . . . . 17
5.5 "atom:id" Element . . . . . . . . . . . . . . . . . . . . 17 5.3 "atom:edit" Element . . . . . . . . . . . . . . . . . . . 17
5.6 "atom:updated" Element . . . . . . . . . . . . . . . . . . 17 5.4 "atom:author" Element . . . . . . . . . . . . . . . . . . 18
5.7 "atom:summary" Element . . . . . . . . . . . . . . . . . . 17 5.5 "atom:contributor" Element . . . . . . . . . . . . . . . . 18
5.8 "atom:content" Element . . . . . . . . . . . . . . . . . . 17 5.6 "atom:id" Element . . . . . . . . . . . . . . . . . . . . 18
5.9 "atom:copyright" Element . . . . . . . . . . . . . . . . . 18 5.7 "atom:updated" Element . . . . . . . . . . . . . . . . . . 18
5.10 "atom:origin" Element . . . . . . . . . . . . . . . . . 18 5.8 "atom:published" Element . . . . . . . . . . . . . . . . . 18
6. Managing Feed State . . . . . . . . . . . . . . . . . . . . 19 5.9 "atom:summary" Element . . . . . . . . . . . . . . . . . . 19
7. Securing Atom Documents . . . . . . . . . . . . . . . . . . 20 5.10 "atom:content" Element . . . . . . . . . . . . . . . . . 19
7.1 Digital Signatures . . . . . . . . . . . . . . . . . . . . 20 5.10.1 "type" attribute . . . . . . . . . . . . . . . . . . 19
7.2 Encryption . . . . . . . . . . . . . . . . . . . . . . . . 20 5.10.2 "src" attribute . . . . . . . . . . . . . . . . . . 19
8. Embedding Atom in Other Formats . . . . . . . . . . . . . . 21 5.10.3 Processing Model . . . . . . . . . . . . . . . . . . 20
9. Extending Atom . . . . . . . . . . . . . . . . . . . . . . . 22 5.11 "atom:copyright" Element . . . . . . . . . . . . . . . . 21
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . 23 5.12 "atom:origin" Element . . . . . . . . . . . . . . . . . 21
11. Security Considerations . . . . . . . . . . . . . . . . . . 24 6. Managing Feed State . . . . . . . . . . . . . . . . . . . . 22
12. Normative References . . . . . . . . . . . . . . . . . . . . 24 7. Securing Atom Documents . . . . . . . . . . . . . . . . . . 23
Author's Address . . . . . . . . . . . . . . . . . . . . . . 25 7.1 Digital Signatures . . . . . . . . . . . . . . . . . . . . 23
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26 7.2 Encryption . . . . . . . . . . . . . . . . . . . . . . . . 23
B. Revision History . . . . . . . . . . . . . . . . . . . . . . 27 8. Embedding Atom in Other Formats . . . . . . . . . . . . . . 24
Intellectual Property and Copyright Statements . . . . . . . 29 9. Extending Atom . . . . . . . . . . . . . . . . . . . . . . . 25
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . 26
11. Security Considerations . . . . . . . . . . . . . . . . . . 27
12. Normative References . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 28
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 29
B. Revision History . . . . . . . . . . . . . . . . . . . . . . 30
Intellectual Property and Copyright Statements . . . . . . . 32
1. Introduction 1. Introduction
Atom is an XML-based document format intended to allow lists of Atom is an XML-based document format intended to allow lists of
related information, known as "feeds", to be synchronised between related information, known as "feeds", to be synchronised between
publishers and consumers. Feeds are composed of a number of items, publishers and consumers. Feeds are composed of a number of items,
known as "entries", each with an extensible set of attached metadata. known as "entries", each with an extensible set of attached metadata.
For example, each entry has a title. For example, each entry has a title.
The primary use case that Atom addresses is the syndication of Web 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 content such as Weblogs and news headlines to Web sites as well as
directly to user agents. However, nothing precludes it from being directly to user agents. However, nothing precludes it from being
used for other purposes and kinds of content. used for other purposes and kinds of content.
Details of comunication protocols between software agents using Atom Details of communication protocols between software agents using Atom
can be found in the Atom Protocol specification [Atom-protocol]. can be found in the Atom Protocol specification [Atom-protocol].
[[ more motivation / design principles ]] [[ more motivation / design principles ]]
1.1 Editorial Notes 1.1 Editorial Notes
The Atom format is a work-in-progress, and this draft is both The Atom format is a work-in-progress, and this draft is both
incomplete and likely to change rapidly. As a result, THE FORMAT incomplete and likely to change rapidly. As a result, THE FORMAT
DESCRIBED BY THIS DRAFT SHOULD NOT BE DEPLOYED, either in production DESCRIBED BY THIS DRAFT SHOULD NOT BE DEPLOYED, either in production
systems or in any non-experimental fashion on the Internet. systems or in any non-experimental fashion on the Internet.
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This document is an early draft and known to be incomplete. Topics This document is an early draft and known to be incomplete. Topics
marked [[like this]] indicate where additional text is likely to be marked [[like this]] indicate where additional text is likely to be
added. added.
1.2 Example 1.2 Example
A minimal, single-entry Atom Feed Document: A minimal, single-entry Atom Feed Document:
<?xml version="1.0" encoding="utf-8"?> <?xml version="1.0" encoding="utf-8"?>
<feed version="draft-ietf-atompub-format-02: do not deploy" <feed version="draft-ietf-atompub-format-03: do not deploy"
xmlns="http://purl.org/atom/ns#draft-ietf-atompub-format-02"> xmlns="http://purl.org/atom/ns#draft-ietf-atompub-format-03">
<head> <head>
<title>Example Feed</title> <title>Example Feed</title>
<link rel="alternate" type="text/html" <link href="http://example.org/"/>
href="http://example.org/"/> <updated>2003-12-13T18:30:02Z</updated>
<modified>2003-12-13T18:30:02Z</modified>
<author> <author>
<name>John Doe</name> <name>John Doe</name>
</author> </author>
</head> </head>
<entry> <entry>
<title>Atom-Powered Robots Run Amok</title> <title>Atom-Powered Robots Run Amok</title>
<link rel="alternate" type="text/html" <link href="http://example.org/2003/12/13/atom03"/>
href="http://example.org/2003/12/13/atom03"/> <id>vemmi://example.org/2003/32397</id>
<id>tag:example.org,2003:3.2397</id> <updated>2003-12-13T18:30:02Z</updated>
<issued>2003-12-13T08:29:29-04:00</issued>
<modified>2003-12-13T18:30:02Z</modified>
</entry> </entry>
</feed> </feed>
1.3 Conformance 1.3 Conformance
[[ talk about atom documents and atom consumers, and how requirements [[ talk about atom documents and atom consumers, and how requirements
are placed on them ]] are placed on them ]]
1.4 Notational Conventions 1.4 Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, [RFC2119]. document are to be interpreted as described in BCP 14, [RFC2119].
This specification uses XML Namespaces [W3C.REC-xml-names-19990114] This specification uses XML Namespaces [W3C.REC-xml-names-19990114]
to uniquely identify XML elements and attribute names. It uses the to uniquely identify XML elements and attribute names. It uses the
following namespace prefixes for the indicated namespace URIs; following namespace prefixes for the indicated namespace URIs;
"atom": http://purl.org/atom/ns#draft-ietf-atompub-format-02 "atom": http://purl.org/atom/ns#draft-ietf-atompub-format-03
Note that the choice of any namespace prefix is arbitrary and not Note that the choice of any namespace prefix is arbitrary and not
semantically significant. semantically significant.
Atom is specified using terms from the XML Infoset Atom is specified using terms from the XML Infoset
[W3C.REC-xml-infoset-20011024]. However, this specification uses a [W3C.REC-xml-infoset-20011024]. However, this specification uses a
shorthand for two common terms; the phrase "Information Item" is shorthand for two common terms; the phrase "Information Item" is
omitted when naming Element Information Items and Attribute omitted when naming Element Information Items and Attribute
Information Items. Information Items.
Therefore, when this specification uses the term "element," it is Therefore, when this specification uses the term "element," it is
refering to an Element Information Item in Infoset terms. Likewise, referring to an Element Information Item in Infoset terms. Likewise,
when it uses the term "attribute," it is refering to an Attribute when it uses the term "attribute," it is referring to an Attribute
Information Item. Information Item.
2. Atom Documents 2. Atom Documents
This specification describes two kinds of Atom Documents; Atom Feed This specification describes two kinds of Atom Documents; Atom Feed
Documents and Atom Entry Documents. Documents and Atom Entry Documents.
An Atom Feed Document is a representation of an Atom feed, including An Atom Feed Document is a representation of an Atom feed, including
metadata about the feed, and some or all of the entries associated metadata about the feed, and some or all of the entries associated
with it. Its document element is atom:feed. with it. Its document element is atom:feed.
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Any element in an Atom Document MAY have an xml:base attribute. XML Any element in an Atom Document MAY have an xml:base attribute. XML
Base [W3C.REC-xmlbase-20010627] processing MUST be applied to any Base [W3C.REC-xmlbase-20010627] processing MUST be applied to any
relative URI reference present in an Atom document. This includes relative URI reference present in an Atom document. This includes
such elements and attributes as specified by Atom itself, as well as such elements and attributes as specified by Atom itself, as well as
those specified by extensions to Atom. those specified by extensions to Atom.
Any element in an Atom Document MAY have an xml:lang attribute, whose Any element in an Atom Document MAY have an xml:lang attribute, whose
content indicates the default natural language of the element's content indicates the default natural language of the element's
content. Requirements regarding the content and interpretation of content. Requirements regarding the content and interpretation of
xml:lang are specified in XML 1.0 [W3C.REC-xml-20040204] Section xml:lang are specified in XML 1.0 [W3C.REC-xml-20040204] Section
2.12. For convenience, the most important are summarised here: 2.12.
o The content of this attribute must be a language tag [RFC3066] or
an empty string (e.g., xml:lang=""), which indicates that there is
no language information available.
o If an element does not have an xml:lang element, the first
xml:lang attribute in its ancestors indicates the natural language
of its content.
[[ feedback as to whether this listing is helpful or not would be
appreciated; re-stating the requirements of other specifications is
tricky. ]]
[[ discussion of URI escaping and i18n ]] [[ discussion of URI escaping and i18n ]]
[[ discussion of white space ]] [[ discussion of white space ]]
Atom is extensible. See the section titled 'Extending Atom' later in Atom is extensible. See the section titled 'Extending Atom' later in
this document for a full description of how Atom Documents can be this document for a full description of how Atom Documents can be
extended. extended.
3. Common Atom Constructs 3. Common Atom Constructs
Many of Atom's elements share a few common structures. This section Many of Atom's elements share a few common structures. This section
defines a few such structures and their requirements, for convenient defines a few such structures and their requirements, for convenient
reference by the appropriate element definitions. reference by the appropriate element definitions.
When an element is identified as being a particular kind of When an element is identified as being a particular kind of
construct, it inherits the corresponding requirements from that construct, it inherits the corresponding requirements from that
construct's definition in this section. construct's definition in this section.
3.1 Content Constructs 3.1 Text Constructs
A Content construct is an element with arbitrary child content, whose A Text construct contains human readable text, usually in fairly
properties are described by the following attributes: small quantities.
3.1.1 "type" Attribute 3.1.1 "type" Attribute
Content constructs MAY have a "type" attribute, whose value indicates Text constructs MAY have a "type" attribute. When present, the value
the media type of the content. When present, this attribute's value MUST be one of "TEXT", "HTML" or "XHTML". If the "type" attribute is
MUST be a media type [RFC2045]. If this attribute is not present, not provided, software MUST behave as though it were present with a
processors MUST behave as if it were present with a value of "text/ value of "TEXT".
plain".
3.1.2 "mode" Attribute Note that MIME media types [RFC2045] are not acceptable values for
the "type" attribute.
Content constructs MAY have a "mode" attribute, whose value indicates If the value is "TEXT", the content of the Text construct MUST NOT
the method used to encode the content. When present, this contain child elements. Such text is intended to be presented to
attribute's value MUST be listed below. If not present, processors humans in a readable fashion. Thus, software MAY display it using
MUST behave as if its value were "xml". normal text rendering techniques such as proportional fonts,
white-space collapsing, and justification.
"xml": A mode attribute with the value "xml" indicates that the If the value of "type" is "HTML", the content of the Text construct
element's content is inline xml (for example, namespace-qualified MUST NOT contain child elements, and SHOULD be suitable for handling
XHTML). by software that knows HTML. The HTML markup must be encoded; for
"escaped": A mode attribute with the value "escaped" indicates that example, "<br>" as "&lt;br>". The HTML markup SHOULD be such that it
the element's content is escaped, as defined in could validly appear directly within an HTML <DIV> element.
[W3C.REC-xml-20040204] (section 4.6). Processors MUST unescape Receiving software which displays the content MAY use the markup to
the element's content before considering it as content of the aid in displaying it.
indicated media type.
"base64": A mode attribute with the value "base64" indicates that If the value of "type" is "XHTML", the content of the Text construct
the element's content is base64-encoded [RFC2045]. Processors MAY contain child elements. The content SHOULD be XHTML text and
MUST decode the element's content before considering it as content markup that could validly appear directly within an xhtml:div
of the the indicated media type. element. Receiving software which displays the content MAY use the
markup to aid in displaying it.
3.2 Person Constructs 3.2 Person Constructs
A Person construct is an element that describes a person, A Person construct is an element that describes a person,
corporation, or similar entity. corporation, or similar entity.
Person constructs MAY be extended by namespace-qualified element Person constructs MAY be extended by namespace-qualified element
children. children.
Ordering of the element children of Person constructs MUST NOT be This specification assigns no significance to the order of appearance
considered significant. of the child elements of atom:entry.
3.2.1 "atom:name" Element 3.2.1 "atom:name" Element
The "atom:name" element's content conveys a human-readable name for The "atom:name" element's content conveys a human-readable name for
the person. Person constructs MUST contain exactly one "atom:name" the person. Person constructs MUST contain exactly one "atom:name"
element. element.
3.2.2 "atom:uri" Element 3.2.2 "atom:uri" Element
The "atom:uri" element's content conveys a URI associated with the The "atom:uri" element's content conveys a URI associated with the
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The "atom:email" element's content conveys an e-mail address The "atom:email" element's content conveys an e-mail address
associated with the persons. Person constructs MAY contain an associated with the persons. Person constructs MAY contain an
atom:email element, but MUST NOT contain more than one. Its content atom:email element, but MUST NOT contain more than one. Its content
MUST be an e-mail address [RFC2822]. MUST be an e-mail address [RFC2822].
3.3 Date Constructs 3.3 Date Constructs
A Date construct is an element whose content MUST conform to the A Date construct is an element whose content MUST conform to the
date-time BNF rule in [RFC3339]. date-time BNF rule in [RFC3339].
3.4 Link Constructs 3.4 Service Constructs
A Link construct is an element that MUST NOT have any child content, A Service construct is an empty element that conveys the URI of an
and has the following attributes: Atom Publishing Protocol [Atom-protocol] service associated with an
entry or feed.
3.4.1 "rel" Attribute A Service construct has the following attribute:
3.4.1 "href" Attribute
The "href" attribute contains the a URI pointing to the endpoint of
the service named by the name attribute. atom:service elements MUST
have a "href" attribute, whose value MUST be a URI.
xml:base processing MUST be applied to the "href" attribute.
3.5 Link Constructs
A Link construct is an empty element that describes a connection from
an Atom document to another Web resource.
3.5.1 "rel" Attribute
The "rel" attribute indicates the type of relationship that the link The "rel" attribute indicates the type of relationship that the link
represents. Link constructs MUST have a rel attribute, whose value represents. Link constructs MAY have a rel attribute, whose value
MUST be one of the values enumerated in the Atom Protocol MUST be a string, and MUST be one of the following values:
specification [Atom-protocol]. "alternate", "related".
3.4.2 "type" Attribute If the "rel" attribute is not present, the link element MUST be
interpreted as if the value "alternate" had been supplied.
3.5.2 "type" Attribute
The "type" attribute indicates an advisory media type; it MAY be used The "type" attribute indicates an advisory media type; it MAY be used
as a hint to determine the type of the representation which should be as a hint to determine the type of the representation which should be
returned when the URI in the href attribute is dereferenced. Note returned when the URI in the href attribute is dereferenced. Note
that the type attribute does not override the actual media type that the type attribute does not override the actual media type
returned with the representation. returned with the representation.
Link constructs MUST have a type attribute, whose value MUST be a Link constructs MAY have a type attribute, whose value MUST be a
media type [RFC2045]. registered media type [RFC2045].
3.4.3 "href" Attribute 3.5.3 "href" Attribute
The "href" attribute contains the link's URI. Link constructs MUST The "href" attribute contains the link's URI. Link constructs MUST
have a href attribute, whose value MUST be a URI [RFC2396]. have a href attribute, whose value MUST be a URI [RFC2396].
xml:base [W3C.REC-xmlbase-20010627] processing MUST be applied to the xml:base [W3C.REC-xmlbase-20010627] processing MUST be applied to the
href attribute's content. href attribute's content.
3.4.4 "hreflang" Attribute 3.5.4 "hreflang" Attribute
The "hreflang" attribute's content describes the language of the The "hreflang" attribute's content describes the language of the
resource pointed to by the href attribute. When used together with resource pointed to by the href attribute. When used together with
the rel="alternate", it implies a translated version of the entry. the rel="alternate", it implies a translated version of the entry.
Link constructs MAY have an hreflang attribute, whose value MUST be a Link constructs MAY have an hreflang attribute, whose value MUST be a
language tag [RFC3066]. language tag [RFC3066].
3.4.5 "title" Attribute 3.5.5 "title" Attribute
The "title" attribute conveys human-readable information about the The "title" attribute conveys human-readable information about the
link. Link constructs MAY have a title attribute. link. Link constructs MAY have a title attribute.
3.5 Identity Constructs 3.6 Identity Constructs
An Identity construct is an element whose content conveys a An Identity construct is an element whose content conveys a
permanent, universally unique identifier for the construct's parent. permanent, universally unique identifier for the construct's parent.
Its content MUST be an absolute URI [RFC2396].
Its content MUST be an absolute URI [RFC2396] that is universally When an Atom document is relocated, migrated, syndicated,
unique; i.e., it MUST NOT change over time, even if the parent feed republished, exported or imported, the content of its Identity
or entry element is relocated, migrated, syndicated, republished, construct MUST NOT change. Put another way, an Identity construct
exported or imported. pertains to all instantiations of a particular Atom entry or feed;
revisions retain the same content in their Identity constructs.
3.5.1 Dereferencing Identity Constructs 3.6.1 Dereferencing Identity Constructs
The content of an Identity construct MAY be dereferencable (e.g. a The content of an Identity construct MAY be dereferencable (e.g. an
HTTP URI). However, processors MUST NOT assume it to be HTTP URI). However, processors MUST NOT assume it to be
dereferencable. dereferencable.
If the identified resource is served dynamically, the content of an The content of an Identity construct MUST be created in a way that
Identity construct MUST be created only once and then stored along assures uniqueness, and it is suggested that the Identity construct
with the resource. The content of an Identity construct MUST NOT be be stored along with the associated resource.
created dynamically.
Because of the risk of confusion between URIs that would be Because of the risk of confusion between URIs that would be
equivalent if dereferenced, the following normalization strategy is equivalent if dereferenced, the following normalization strategy is
strongly encouraged when generating Identity constructs: strongly encouraged when generating Identity constructs:
o Provide the scheme in lowercase characters. o Provide the scheme in lowercase characters.
o Provide the host, if any, in lowercase characters. o Provide the host, if any, in lowercase characters.
o Only perform percent-encoding where it is essential. o Only perform percent-encoding where it is essential.
o Use uppercase A-through-F characters when percent-encoding. o Use uppercase A-through-F characters when percent-encoding.
o Prevent dot-segments appearing in paths. o Prevent dot-segments appearing in paths.
o For schemes that define a default authority, use an empty o For schemes that define a default authority, use an empty
authority if the default is desired. authority if the default is desired.
o For schemes that define an empty path to be equivalent to a path o For schemes that define an empty path to be equivalent to a path
of "/", use "/". of "/", use "/".
o For schemes that define a port, use an empty port if the default o For schemes that define a port, use an empty port if the default
is desired. is desired.
o Preserve empty fragment identifiers and queries. o Preserve empty fragment identifiers and queries.
o Ensure that all portions of the URI are utf-8 encoded NFC form o Ensure that all portions of the URI are utf-8 encoded NFC form
Unicode strings. Unicode strings.
3.5.2 Comparing Identity Constructs 3.6.2 Comparing Identity Constructs
Instances of Identity constructs can be compared to determine whether Instances of Identity constructs can be compared to determine whether
a entry or feed is the same as one seen before. Processors MUST an entry or feed is the same as one seen before. Processors MUST
compare Identity constructs on a character-by-character basis in a compare Identity constructs on a character-by-character basis in a
case-sensitive fashion. case-sensitive fashion.
As a result, two URIs that resolve to the same resource but are not As a result, two URIs that resolve to the same resource but are not
character-for-character identical will be considered different for character-for-character identical will be considered different for
the purposes of Identifier comparison. the purposes of Identifier comparison.
For example, "http://www.example.org/thing", For example, "http://www.example.org/thing",
"http://www.example.org/Thing", "http://www.EXAMPLE.org/thing" and "http://www.example.org/Thing", "http://www.EXAMPLE.org/thing" and
"HTTP://www.example.org/thing" will all be considered different "HTTP://www.example.org/thing" will all be considered different
identifiers, despite their differences in case. identifiers, despite their differences in case.
Likewise, "http://www.example.com/~bob", Likewise, "http://www.example.com/~bob",
"http://www.example.com/%7ebob" and "http://www.example.com/%7Ebob" "http://www.example.com/%7ebob" and "http://www.example.com/%7Ebob"
will all be considered different identifiers, because URI %-escaping will all be considered different identifiers, because URI %-escaping
is significant for the purposes of comparison. is significant for the purposes of comparison.
XML character and entity references MUST be converted into characters
before comparison.
4. The "atom:feed" Element 4. The "atom:feed" Element
The "atom:feed" element is the document (i.e., top-level) element of 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 an Atom Feed Document, acting as a container for metadata and data
associated with the feed. Its first element child MUST be atom:head, associated with the feed. Its first element child MUST be atom:head,
which MAY be followed zero or more atom:entry child elements. which MAY be followed zero or more atom:entry child elements.
4.1 "version" Attribute 4.1 "version" Attribute
atom:feed elements MUST have a "version" attribute whose content atom:feed elements MUST have a "version" attribute whose content
indicates the version of the Atom specification that the feed indicates the version of the Atom specification that the feed
conforms to. The content of this attribute is unstructured text. conforms to. The content of this attribute is unstructured text.
The version identifier for this specification is The version identifier for this specification is
"draft-ietf-atompub-format-02: do not deploy". "draft-ietf-atompub-format-03: do not deploy".
4.2 The "atom:head" Element 4.2 The "atom:head" Element
The atom:head element acts as a container for metadata about the feed The atom:head element acts as a container for metadata about the feed
itself. itself.
The atom:head element MAY contain any namespace-qualified The atom:head element MAY contain any namespace-qualified
[W3C.REC-xml-names-19990114] elements as children. Ordering of the [W3C.REC-xml-names-19990114] elements as children. This
element children of atom:head element MUST NOT be considered specification assigns no significance to the order of appearance of
significant. the child elements of atom:head.
The following child elements are defined by this specification (note The following child elements are defined by this specification (note
that the presence of some of these elements is required): that the presence of some of these elements is required):
4.2.1 "atom:title" Element 4.2.1 "atom:title" Element
The "atom:title" element is a Content construct that conveys a The "atom:title" element is a Text construct that conveys a
human-readable title for the feed. atom:head elements MUST contain human-readable title for the feed. atom:head elements MUST contain
exactly one atom:title element. exactly one atom:title element.
4.2.2 "atom:link" Element 4.2.2 "atom:link" Element
The "atom:link" element is a Link construct that conveys a URI The "atom:link" element is a Link construct that conveys a URI
associated with the feed. The nature of the relationship is associated with the feed. The nature of the relationship is
determined by the construct's rel attribute. determined by the construct's rel attribute.
atom:head elements MUST contain at least one atom:link element with a atom:head elements MUST contain at least one atom:link element with a
skipping to change at page 14, line 12 skipping to change at page 14, line 12
with a rel attribute value of "alternate" that has the same type with a rel attribute value of "alternate" that has the same type
attribute value. attribute value.
If a feed's atom:link element with type="alternate" resolves to an If a feed's atom:link element with type="alternate" resolves to an
HTML document, then that document SHOULD have a autodiscovery link HTML document, then that document SHOULD have a autodiscovery link
element [Atom-autodiscovery] that reflects back to the feed. element [Atom-autodiscovery] that reflects back to the feed.
atom:head elements MAY contain additional atom:link elements beyond atom:head elements MAY contain additional atom:link elements beyond
those described above. those described above.
4.2.3 "atom:author" Element 4.2.3 "atom:introspection" Element
The "atom:introspection" element is a Service construct that conveys
the URI of an introspection file associated with the feed. atom:head
elements MUST NOT contain more than one atom:introspection element.
4.2.4 "atom:post" Element
The "atom:post" element is a Service construct that conveys the URI
used to add entries to the feed. atom:head elements MUST NOT contain
more than one atom:post element.
4.2.5 "atom:author" Element
The "atom:author" element is a Person construct that indicates the The "atom:author" element is a Person construct that indicates the
default author of the feed. atom:head elements MUST contain exactly default author of the feed. atom:head elements MUST contain exactly
one atom:author element, UNLESS all of the atom:feed element's child one atom:author element, UNLESS all of the atom:feed element's child
atom:entry elements contain an atom:author element. atom:head atom:entry elements contain an atom:author element. atom:head
elements MUST NOT contain more than one atom:author element. elements MUST NOT contain more than one atom:author element.
[[explain inheritence]] [[explain inheritance]]
4.2.4 "atom:contributor" Element 4.2.6 "atom:contributor" Element
The "atom:contributor" element is a Person construct that indicates a The "atom:contributor" element is a Person construct that indicates a
person or other entity who contributes to the feed. atom:head person or other entity who contributes to the feed. atom:head
elements MAY contain one or more atom:contributor elements. elements MAY contain one or more atom:contributor elements.
4.2.5 "atom:tagline" Element 4.2.7 "atom:tagline" Element
The "atom:tagline" element is a Content construct that conveys a The "atom:tagline" element is a Text construct that conveys a
human-readable description or tagline for the feed. atom:head human-readable description or tagline for the feed. atom:head
elements MAY contain an atom:tagline element, but MUST NOT contain elements MAY contain an atom:tagline element, but MUST NOT contain
more than one. more than one.
4.2.6 "atom:id" Element 4.2.8 "atom:id" Element
The "atom:id" element is an Identity construct that conveys a The "atom:id" element is an Identity construct that conveys a
permanent, universally unique identifier for a feed. atom:head permanent, universally unique identifier for a feed. atom:head
elements MAY contain an atom:id element, but MUST NOT contain more elements MAY contain an atom:id element, but MUST NOT contain more
than one. than one.
4.2.7 "atom:generator" Element 4.2.9 "atom:generator" Element
The "atom:generator" element's content indentifies the software agent The "atom:generator" element's content identifies the software agent
used to generate the feed, for debugging and other purposes. used to generate the feed, for debugging and other purposes.
atom:head elements MAY contain an atom:generator element, but MUST atom:head elements MAY contain an atom:generator element, but MUST
NOT contain more than one. NOT contain more than one.
The content of this element, when present, MUST be a string that is a The content of this element, when present, MUST be a string that is a
human-readable name for the generating agent. human-readable name for the generating agent.
The atom:generator element MAY have a "uri" attribute whose value The atom:generator element MAY have a "uri" attribute whose value
MUST be a URI. When dereferenced, that URI SHOULD produce a MUST be a URI. When dereferenced, that URI SHOULD produce a
representation that is relevant to that agent. representation that is relevant to that agent.
The atom:generator element MAY have a "version" attribute that The atom:generator element MAY have a "version" attribute that
indicates the version of the generating agent. When present, its indicates the version of the generating agent. When present, its
value is unstructured text. value is unstructured text.
4.2.8 "atom:copyright" Element 4.2.10 "atom:copyright" Element
The "atom:copyright" element is Content construct that conveys a The "atom:copyright" element is Text construct that conveys a
human-readable copyright statement for the feed. atom:head elements human-readable copyright statement for the feed. atom:head elements
MAY contain an atom:copyright element, but MUST NOT contain more than MAY contain an atom:copyright element, but MUST NOT contain more than
one. one.
The atom:copyright element SHOULD NOT be used to convey The atom:copyright element SHOULD NOT be used to convey
machine-readable licensing information. machine-readable licensing information.
[[Is the following paragraph bogus amateur lawyering? The first
paragraph seems sufficient.]]
The atom:copyright element may be assumed to apply to all entries The atom:copyright element may be assumed to apply to all entries
contained by the feed except those entries which contain contained by the feed except those entries which contain
atom:copyright elements. The atom:copyright element MUST, if atom:copyright elements. The atom:copyright element MUST, if
present, be considered to apply to the feed as a collection of present, be considered to apply to the feed as a collection of
entries. entries.
4.2.9 "atom:info" Element 4.2.11 "atom:info" Element
The "atom:info" element is a Content construct that conveys a The "atom:info" element is a Text construct that conveys a
human-readable explanation of the feed format itself. atom:head human-readable explanation of the feed format itself. atom:head
elements MAY contain an atom:info element, but MUST NOT contain more elements MAY contain an atom:info element, but MUST NOT contain more
than one. than one.
The atom:info element SHOULD NOT considered meaningful by processors; The atom:info element SHOULD NOT considered meaningful by processors;
it is a convenience to publishers in certain situations. it is a convenience to publishers in certain situations.
4.2.10 "atom:modified" Element 4.2.12 "atom:updated" Element
The "atom:modified" element is a Date construct that indicates the The "atom:updated" element is a Date construct indicating the most
time when the state of the feed was last modified, including any recent instant in time when a change to the feed was made that the
changes to entries therein. atom:head elements MUST contain exactly publisher wishes to bring to the attention of subscribers. For
one atom:modified element. example, such changes might not include minor adjustments like
spelling and grammatical corrections.
The content of an atom:modified element SHOULD have a time zone whose atom:head elements MUST contain exactly one atom:updated element.
value MUST be "UTC".
5. The "atom:entry" Element 5. The "atom:entry" Element
The "atom:entry" element represents an individual entry. This The "atom:entry" element represents an individual entry. This
element can appear as a child of the atom:feed element, or it can 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 standalone Atom appear as the document (i.e., top-level) element of a standalone Atom
Entry Document. Entry Document.
When appearing in an Atom Entry Document, atom:entry elements MUST When appearing in an Atom Entry Document, atom:entry elements MUST
have a "version" attribute whose content indicates the version of the have a "version" attribute whose content indicates the version of the
Atom specification that the entry conforms to. Atom specification that the entry conforms to.
The version identifier for this specification is The version identifier for this specification is
"draft-ietf-atompub-format-02: do not deploy". "draft-ietf-atompub-format-03: do not deploy".
The atom:entry element MAY contain any namespace-qualified The atom:entry element MAY contain any namespace-qualified
[W3C.REC-xml-names-19990114] elements as children. Ordering of the [W3C.REC-xml-names-19990114] elements as children. This
element children of atom:entry element MUST NOT be considered specification assigns no significance to the order of appearance of
significant. the child elements of atom:entry.
The following child elements are defined by this specification (note The following child elements are defined by this specification (note
that it requires the presence of some of these elements): that it requires the presence of some of these elements):
5.1 "atom:title" Element 5.1 "atom:title" Element
The "atom:title" element is a Content construct that conveys a The "atom:title" element is a Text construct that conveys a
human-readable title for the entry. atom:entry elements MUST have human-readable title for the entry. atom:entry elements MUST have
exactly one "atom:title" element. exactly one "atom:title" element.
5.2 "atom:link" Element 5.2 "atom:link" Element
The "atom:link" element is a Link construct that conveys a URI The "atom:link" element is a Link construct that conveys a URI
associated with the entry. The nature of the relationship as well as associated with the entry. The nature of the relationship as well as
the link itself is determined by the element's content. the link itself is determined by the element's content.
atom:entry elements MUST contain at least one atom:link element with atom:entry elements MUST contain at least one atom:link element with
a rel attribute value of "alternate". a rel attribute value of "alternate".
atom:entry elements MUST NOT contain more than one atom:link element atom:entry elements MUST NOT contain more than one atom:link element
with a rel attribute value of "alternate" that has the same type with a rel attribute value of "alternate" that has the same type
attribute value. attribute value.
atom:entry elements MAY contain additional atom:link elements beyond atom:entry elements MAY contain additional atom:link elements beyond
those described above. those described above.
5.3 "atom:author" Element 5.3 "atom:edit" Element
The "atom:edit" element is a Service construct that conveys the URI
used to retrieve and edit the source representation of the entry.
atom:entry elements MUST NOT contain more than one atom:edit element.
5.4 "atom:author" Element
The "atom:author" element is a Person construct that indicates the The "atom:author" element is a Person construct that indicates the
default author of the entry. atom:entry elements MUST contain default author of the entry. atom:entry elements MUST contain
exactly one atom:author element, unless, in an Atom Feed Document, exactly one atom:author element, unless, in an Atom Feed Document,
the atom:head element contains an atom:author element itself. the atom:head element contains an atom:author element itself.
atom:entry elements MUST NOT contain more than one atom:author atom:entry elements MUST NOT contain more than one atom:author
element. element.
5.4 "atom:contributor" Element 5.5 "atom:contributor" Element
The "atom:contributor" element is a Person construct that indicates a The "atom:contributor" element is a Person construct that indicates a
person or other entity who contributes to the entry. atom:entry person or other entity who contributes to the entry. atom:entry
elements MAY contain one or more atom:contributor elements. elements MAY contain one or more atom:contributor elements.
5.5 "atom:id" Element 5.6 "atom:id" Element
The "atom:id" element is an Identity construct that conveys a The "atom:id" element is an Identity construct that conveys a
permanent, universally unique identifier for an entry. atom:entry permanent, universally unique identifier for an entry. atom:entry
elements MUST contain exactly one atom:id element. elements MUST contain exactly one atom:id element.
5.6 "atom:updated" Element 5.7 "atom:updated" Element
The "atom:updated" element is a Date construct indicating the most The "atom:updated" element is a Date construct indicating the most
recent instant in time when a change to the entry was made that the recent instant in time when a change to the entry was made that the
publisher wishes to bring to the attention of subscribers. For publisher wishes to bring to the attention of subscribers. For
example, such changes might not include minor adjustments like example, such changes might not include minor adjustments like
spelling and grammatical corrections. spelling and grammatical corrections.
atom:entry elements MUST contain exactly one atom:updated element. atom:entry elements MUST contain exactly one atom:updated element.
Publishers MAY change the value of this element over time. Publishers MAY change the value of this element over time.
Processors MAY present entries sorted using this value. Processors Processors MAY present entries sorted using this value. Processors
MAY choose not to present entries until the instant in time specified MAY choose not to present entries until the instant in time specified
in the atom:updated element has passed. in the atom:updated element has passed.
5.7 "atom:summary" Element 5.8 "atom:published" Element
The "atom:summary" element is a Content construct that conveys a The "atom:published" element is a Date construct indicating an
short summary, abstract or excerpt of the entry. atom:entry elements instant in time associated with an event early in the life cycle of
MAY contain an atom:summary element, but MUST NOT contain more than the entry. Typically, atom:published will be associated with the
one. initial creation or first availability of the resource.
5.8 "atom:content" Element atom:entry elements MAY contain an atom:published element, but MUST
NOT contain more than one.
The "atom:content" element is a Content construct that conveys the Processors MAY present entries sorted using this value. Processors
content of the entry. atom:entry elements MAY contain one or more MAY choose not to present entries until the instant in time specified
atom:content elements. in the atom:published element has passed.
If @type="multipart/alternative", @mode MUST NOT be specified, and 5.9 "atom:summary" Element
content element MUST contain 1 or more content elements. These
content elements MUST NOT specify @type="multipart/alternative" (i.e.
only one level of nesting is allowed). Consumers SHOULD look at all The "atom:summary" element is a Text construct that conveys a short
alternative content elements and determine which one is most summary, abstract or excerpt of the entry. atom:entry elements MAY
suitable, based on which @type and @mode the consumer supports, and contain an atom:summary element, but MUST NOT contain more than one.
preferences specified by the end user (if any). Consumers SHOULD NOT
render more than one content alternative.
5.9 "atom:copyright" Element atom:entry elements MUST contain an atom:summary element in any of
the following cases:
The "atom:copyright" element is a Content construct that conveys a o the atom:entry element contains no atom:content element.
o the atom:entry contains an atom:content which has a "src"
attribute (and is thus empty).
o the atom:entry contains content which is encoded in Base64; i.e.
the "type" attribute of atom:content is a MIME media type
[RFC2045] and does not begin with "text/" nor end with "+xml".
5.10 "atom:content" Element
The "atom:content" element either contains or links to the content of
the entry. atom:entry elements MUST contain zero or one atom:content
elements.
5.10.1 "type" attribute
atom:content MAY have a "type" attribute, When present, the value MAY
be one of "TEXT", "HTML", or "XHTML". Failing that, it MUST be a
MIME media type [RFC2045] in which, to use the terminology of Section
5 of [RFC2045], the top level is a discrete type. If the type
attribute is not provided, software MUST behave as though it were
present with a value of "TEXT".
5.10.2 "src" attribute
atom:content MAY have a "src" attribute, whose value MUST be a URI.
If the "src" attribute is present, software MAY use the URI to
retrieve the content. If the "src" attribute is present,
atom:content MUST be empty. That is to say, the content may be
retrievable using "src=" URI, or it may be contained within
atom:content, but not both.
If the "src" attribute is present, the "type" attribute MUST be
provided and MUST be a MIME media type [RFC2045], rather than "TEXT",
"HTML", or "XHTML". The value is advisory; that is to say, upon
dereferencing the URI to retrieve the content, if the server
providing that content also provides a media type, the
server-provided media type is authoritative.
If the value of type begins with "text/" or ends with "+xml", the
content SHOULD be local; that is to say, no "src" attribute should be
provided.
5.10.3 Processing Model
Software MUST apply the following rules in succession in the order
below to ascertain the rules governing the content of "atom:content".
1. If the value 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, software MAY display it
using normal text rendering techniques such as proportional
fonts, white-space collapsing, and justification.
2. If the value of "type" is "HTML", the content of atom:content
MUST NOT contain child elements, and SHOULD be suitable for
handling by software that knows HTML. The HTML markup must be
encoded; for example, "<br>" as "&lt;br>". The HTML markup
SHOULD be such that it could validly appear directly within an
HTML <DIV> element. Receiving software which displays the
content SHOULD use the markup to aid in displaying it.
3. If the value of "type" is "XHTML", the content of atom:content
MAY contain child elements. The content SHOULD be XHTML text and
markup that could validly appear directly within an xhtml:div
element. Receiving software which displays the content SHOULD
use the markup to aid in displaying it.
4. If the value of "type" ends with "+xml" or "/xml", the content of
atom:content may include child elements, and SHOULD be suitable
for handling by software that knows 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 which would serve as the root element of the XML document
of the indicated type.
5. If the value of "type" begins with "text/" 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 [RFC3548], which when decoded SHOULD
be suitable for handling by software that knows the indicated
media type. In this case, the characters in the Base64 encoding
may be preceded and followed in the atom:content element by
whitespace, and lines are separated by a single newline (U+000A)
character, as required by XML.
5.11 "atom:copyright" Element
The "atom:copyright" element is a Text construct that conveys a
human-readable copyright statement for the entry. atom:entry human-readable copyright statement for the entry. atom:entry
elements MAY contain an atom:copyright element, but MUST NOT contain elements MAY contain an atom:copyright element, but MUST NOT contain
more than one. more than one.
The atom:copyright element SHOULD NOT be used to convey The atom:copyright element SHOULD NOT be used to convey
machine-readable licensing information. machine-readable licensing information.
If an atom:entry element does not contain an atom:copyright element, If an atom:entry element does not contain an atom:copyright element,
then the atom:copyright element of the containing atom:feed element's then the atom:copyright element of the containing atom:feed element's
atom:head element, if present, should be considered to apply to the atom:head element, if present, should be considered to apply to the
entry. entry.
5.10 "atom:origin" Element 5.12 "atom:origin" Element
The "atom:origin" element's content conveys the original source of The "atom:origin" element's content conveys the original source of
the entry; e.g., the feed where the entry was first published. the entry; e.g., the feed where the entry was first published.
If the source is an Atom Feed Document, then the content of If the source is an Atom Feed Document, then the content of
atom:origin MUST be the same, character-for-character, as that of the atom:origin MUST be the same, character-for-character, as that of the
atom:id element in that document's atom:head section (i.e., the XPath atom:id element in that document's atom:head section (i.e., the XPath
expression "/atom:feed/atom:head/atom:id"). expression "/atom:feed/atom:head/atom:id").
The content of this element MUST be a URI. atom:entry elements MAY The content of this element MUST be a URI. atom:entry elements MAY
skipping to change at page 20, line 33 skipping to change at page 23, line 33
signature because they are not capable of verifying it; they MUST signature because they are not capable of verifying it; they MUST
continue processing and MAY inform the user of their failure to continue processing and MAY inform the user of their failure to
validate the signature. validate the signature.
In other words, the presence of an element with the namespace URI 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" "http://www.w3.org/2000/09/xmldsig#" and a local name of "Signature"
as a child of the document element must not cause a processor to fail as a child of the document element must not cause a processor to fail
merely because of its presence. merely because of its presence.
Other elements in an Atom document MUST NOT be signed unless their Other elements in an Atom document MUST NOT be signed unless their
defintions explicitly specify such a capability. definitions explicitly specify such a capability.
7.2 Encryption 7.2 Encryption
The document element of an Atom document (i.e., atom:feed in an Atom The document element of an Atom document (i.e., atom:feed in an Atom
Feed Document, atom:entry in an Atom Entry Document) MAY be Feed Document, atom:entry in an Atom Entry Document) MAY be
encrypted, using the mechanisms described by XML Encryption Syntax encrypted, using the mechanisms described by XML Encryption Syntax
and Processing [W3C.REC-xmlenc-core-20021210]. Other XML encryption and Processing [W3C.REC-xmlenc-core-20021210]. Other XML encryption
mechanisms MUST NOT be used on the document element of an Atom mechanisms MUST NOT be used on the document element of an Atom
document. document.
skipping to change at page 24, line 45 skipping to change at page 27, line 45
[RFC3023] Murata, M., St. Laurent, S. and D. Kohn, "XML Media [RFC3023] Murata, M., St. Laurent, S. and D. Kohn, "XML Media
Types", RFC 3023, January 2001. Types", RFC 3023, January 2001.
[RFC3066] Alvestrand, H., "Tags for the Identification of [RFC3066] Alvestrand, H., "Tags for the Identification of
Languages", BCP 47, RFC 3066, January 2001. Languages", BCP 47, RFC 3066, January 2001.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, July 2002. Timestamps", RFC 3339, July 2002.
[RFC3548] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 3548, July 2003.
[W3C.NOTE-datetime-19980827] [W3C.NOTE-datetime-19980827]
Wolf, M. and C. Wicksteed, "Date and Time Formats", W3C Wolf, M. and C. Wicksteed, "Date and Time Formats", W3C
NOTE NOTE-datetime-19980827, August 1998. NOTE NOTE-datetime-19980827, August 1998.
[W3C.REC-xml-20040204] [W3C.REC-xml-20040204]
Yergeau, F., Bray, T., Paoli, J., Sperberg-McQueen, C. and Yergeau, F., Paoli, J., Sperberg-McQueen, C., Bray, T. and
E. Maler, "Extensible Markup Language (XML) 1.0 (Third E. Maler, "Extensible Markup Language (XML) 1.0 (Third
Edition)", W3C REC REC-xml-20040204, February 2004. Edition)", W3C REC REC-xml-20040204, February 2004.
[W3C.REC-xml-infoset-20011024] [W3C.REC-xml-infoset-20011024]
Cowan, J. and R. Tobin, "XML Information Set", W3C REC Tobin, R. and J. Cowan, "XML Information Set", W3C
REC-xml-infoset-20011024, October 2001. FirstEdition REC-xml-infoset-20011024, October 2001.
[W3C.REC-xml-names-19990114] [W3C.REC-xml-names-19990114]
Bray, T., Hollander, D. and A. Layman, "Namespaces in Hollander, D., Bray, T. and A. Layman, "Namespaces in
XML", W3C REC REC-xml-names-19990114, January 1999. XML", W3C REC REC-xml-names-19990114, January 1999.
[W3C.REC-xmlbase-20010627] [W3C.REC-xmlbase-20010627]
Marsh, J., "XML Base", W3C REC REC-xmlbase-20010627, June Marsh, J., "XML Base", W3C REC REC-xmlbase-20010627, June
2001. 2001.
[W3C.REC-xmldsig-core-20020212] [W3C.REC-xmldsig-core-20020212]
Eastlake, D., Reagle, J. and D. Solo, "XML-Signature Solo, D., Reagle, J. and D. Eastlake, "XML-Signature
Syntax and Processing", W3C REC REC-xmldsig-core-20020212, Syntax and Processing", W3C REC REC-xmldsig-core-20020212,
February 2002. February 2002.
[W3C.REC-xmlenc-core-20021210] [W3C.REC-xmlenc-core-20021210]
Eastlake, D. and J. Reagle, "XML Encryption Syntax and Reagle, J. and D. Eastlake, "XML Encryption Syntax and
Processing", W3C REC REC-xmlenc-core-20021210, December Processing", W3C REC REC-xmlenc-core-20021210, December
2002. 2002.
[1] <http://www.imc.org/atom-syntax/index.html> [1] <http://www.imc.org/atom-syntax/index.html>
[2] <http://www.intertwingly.net/wiki/pie/FrontPage> [2] <http://www.intertwingly.net/wiki/pie/FrontPage>
Author's Address Authors' Addresses
Mark Nottingham (editor) Mark Nottingham (editor)
EMail: mnot@pobox.com EMail: mnot@pobox.com
URI: http://www.mnot.net/ URI: http://www.mnot.net/
Robert Sayre (editor)
Boswijck Memex Consulting
EMail: rfsayre@boswijck.com
URI: http://boswijck.com
Appendix A. Contributors Appendix A. Contributors
The following people contributed to preliminary drafts of this The following people contributed to preliminary drafts of this
document: Tim Bray, Mark Pilgrim, and Sam Ruby. The content and document: Tim Bray, Mark Pilgrim, and Sam Ruby. The content and
concepts within are a product of the Atom community and the Atom concepts within are a product of the Atom community and the Atom
Publishing Format and Protocol Working Group. Publishing Format and Protocol Working Group.
Appendix B. Revision History Appendix B. Revision History
[[ this section should be removed before final publication. ]] [[ this section should be removed before final publication. ]]
-03: Move definition of Link @rel to format spec, restrict
acceptable values (PaceMoveLinkElement, PaceLinkAttrDefaults).
Add Service Construct, head/post, head/introspection, entry/edit
(PaceServiceElement).
Add Text Construct, entry/content (PaceReformedContent3).
Add entry/published (PaceDatePublished).
Adjust definition of Identity Construct per chairs' direction to
"fix it."
Add Sayre to editors.
-02: Removed entry/modified, entry/issued, entry/created; added -02: Removed entry/modified, entry/issued, entry/created; added
entry/updated (PaceDateUpdated). entry/updated (PaceDateUpdated).
Changed date construct from W3C date-time to RFC3339 Changed date construct from W3C date-time to RFC3339
(PaceDateUpdated). (PaceDateUpdated).
Feed links to HTML pages should be reflected back Feed links to HTML pages should be reflected back
(PaceLinkReflection). (PaceLinkReflection).
Added Identity construct (PaceIdConstruct). Added Identity construct (PaceIdConstruct).
Changed feed/id and entry/id to be Identity constructs Changed feed/id and entry/id to be Identity constructs
(PaceIdConstruct). (PaceIdConstruct).
Changed entry/origin's content so that it's the same as the feed's Changed entry/origin's content so that it's the same as the feed's
 End of changes. 

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