hatom

hAtom 0.1

hAtom is a microformat for content that can be syndicated, primarily but not exclusively weblog postings. hAtom is based on a subset of the Atom syndication format. hAtom is one of several microformats open standards.

Draft Specification

Editor/Author

• David Janes, BlogMatrix, Inc.

Contributors

• Benjamin Carlyle
• Tantek Çelik, Technorati, Inc.

Copyright

This specification is (C) 2005-2024 by the authors. However, the authors intend to submit (or already have submitted, see details in the spec) this specification to a standards body with a liberal copyright/licensing policy such as the GMPG, IETF, and/or W3C. Anyone wishing to contribute should read their copyright principles, policies and licenses (e.g. the GMPG Principles) and agree to them, including licensing of all contributions under all required licenses (e.g. CC-by 1.0 and later), before contributing.

Patents

This specification is subject to a royalty free patent policy, e.g. per the W3C Patent Policy, and IETF RFC3667 & RFC3668.

Introduction

hAtom is a microformat for identifying semantic information in weblog posts and practically any other place Atom may be used, such as news articles. hAtom content is easily added to most blogs by simple modifications to the blog's template definitions.

Semantic XHTML Design Principles

Note: the Semantic XHTML Design Principles were written primarily within the context of developing hCard and hCalendar, thus it may be easier to understand these principles in the context of the hCard design methodology (i.e. read that first). Tantek

XHTML is built on XML, and thus XHTML based formats can be used not only for convenient display presentation, but also for general purpose data exchange. In many ways, XHTML based formats exemplify the best of both HTML and XML worlds. However, when building XHTML based formats, it helps to have a guiding set of principles.

1. Reuse the schema (names, objects, properties, values, types, hierarchies, constraints) as much as possible from pre-existing, established, well-supported standards by reference. Avoid restating constraints expressed in the source standard. Informative mentions are ok.
   1. For types with multiple components, use nested elements with class names equivalent to the names of the components.
   2. Plural components are made singular, and thus multiple nested elements are used to represent multiple text values that are comma-delimited.
2. Use the most accurately precise semantic XHTML building block for each object etc.
3. Otherwise use a generic structural element (e.g. <span> or <div>), or the appropriate contextual element (e.g. an <li> inside a <ul> or <ol>).
4. Use class names based on names from the original schema, unless the semantic XHTML building block precisely represents that part of the original schema. If names in the source schema are case-insensitive, then use an all lowercase equivalent. Components names implicit in prose (rather than explicit in the defined schema) should also use lowercase equivalents for ease of use. Spaces in component names become dash '-' characters.
5. Finally, if the format of the data according to the original schema is too long and/or not human-friendly, use <abbr> instead of a generic structural element, and place the literal data into the 'title' attribute (where abbr expansions go), and the more brief and human readable equivalent into the element itself. Further informative explanation of this use of <abbr>: Human vs. ISO8601 dates problem solved

Format

In General

The Atom Syndication Format provides the conceptual basis for this microformat, with the following caveats:

• Atom provides a lot more functionality than we need for a "blog post" microformat, so we've taken the minimal number of elements needed.
• the "logical" model of hAtom is that of Atom. If there is a conflict, Atom should be taken as correct.
• the "physical" model of hAtom -- the actual writing of elements -- is a lot more varied than Atom provides for, due to the variety of ways weblogs are actually produced in the wild. The hAtom microformat provides a number of rules for "bridging the gap"

Schema

Schema elements are based on the Atom nomenclature and follow the microformat pattern of prefixing a unique identifier (in this case, 'h') on the outermost container elements -- the Feed or Entry. The parts of this microformat are based on analysis of many weblog, bulletin board and media posts and can be read blog-post-brainstorming#Discovered_Elements.

The hAtom schema consists of the following:

• hfeed (hfeed). optional.
• hentry (hentry).
  • entry-title. required. text.
  • entry-content. optional (see field description). text.
  • entry-summary. optional. text.
  • updated. required using datetime-design-pattern.
  • published. optional using datetime-design-pattern.
  • author. required using hCard.
  • bookmark (permalink). optional, using rel-bookmark.
  • tags. optional. keywords or phrases, using rel-tag.

Some required elements have defaults if missing, see below.

Field and Element Details

Feed

• a Feed element is identified by the class name hfeed
• a Feed element represents the concept of an Atom feed
• the Feed element is optional and, if missing, is assumed to be the page
• hAtom documents MAY have multiple Feed elements

Feed Category

• a Feed Category element is identified by rel-tag
• a Feed MAY have a Feed Category
• a Feed Category element represents the concept of an Atom category inside a feed
• Feed Category elements MUST appear inside a Feed element but not inside an Entry element
• the rel-tag href encodes the atom category:term; the link text defines the atom category:label

Entry

• an Entry element is identified by class name hentry
• an Entry element represents the concept of an Atom entry
• any microformat content inside a <blockquote> or <q> element within the Entry should not be considered part of the Entry.

This allows quoting other microformated data without worry of corrupting the model

Entry Category

• an Entry Category element is identified by rel-tag
• an Entry MAY have an Entry Category
• an Entry Category element represents the concept of an Atom category inside an entry
• the rel-tag href encodes the atom category:term; the link text defines the atom category:label

Entry Title

• an Entry Title element is identified by the class name entry-title
• an Entry SHOULD have an Entry Title
• an Entry Title element represents the concept of an Atom entry title
• if the Entry Title is missing, use
  • the first <h#> element in the Entry, or
  • the <title> of the page, if there is no enclosing Feed element, or
  • assume it is the empty string

Entry Content

• an Entry Content element is identified by class name entry-content
• an Entry SHOULD have Entry Content
• an Entry Content element represents the concept of an Atom content
• an Entry MAY have 0 or more Entry Content elements. The "logical Entry Content" of an Entry is the concatenation, in order of appearance, of all the Entry Contents within the Entry

Many weblogs split content into multiple sections with a "Read More" link and javascript tricks. This is also needed in cases where Entry Titles are coded inline and are considered part of the content.

• if the Entry Content is missing, assume it is the empty string

Entry Summary

• an Entry Summary element is identified by class name entry-summary
• an Entry Summary element represents the concept of an Atom summary
• an Entry MAY have 0 or more Entry Summary elements. The "logical Entry Summary" of an Entry is the concatenation, in order of appearance, of all the Entry Summarys within the Entry

Entry Permalink

• an Entry Permalink element is identified by rel-bookmark
• an Entry SHOULD have an Entry Permalink
• an Entry Permalink element represents the concept of an Atom link in an entry
• if the Entry Permalink is missing, use the URI of the page; if the Entry has an "id" attribute, add that as a fragment to the page URI to distinguish individual entries

Entry Updated

• an Entry Updated element is identified by class name updated
• an Entry Updated element represents the concept of Atom updated
• an Entry SHOULD have an Entry Updated element
• use the datetime-design-pattern to encode the updated datetime
• if there is no Entry Updated element,
  • use the Entry Published element, if present
  • otherwise the page is invalid hAtom

Entry Published

• an Entry Published element is identified by the class name published
• an Entry Published element represents the concept of Atom published
• use the datetime-design-pattern to encode the published datetime

Entry Author

• an Entry Author element is represented by class name author
• an Entry Author element represents the concept of an Atom author
• an Entry Author element MUST be encoded in an hCard
• an Entry Author element SHOULD be encoded in an <address> element
• an Entry SHOULD have at least one Entry Author element
• an Entry MAY have more than one Entry Author elements
• if the Entry Author is missing
  • find the Nearest In Parent <address> element(s) with class name author and that is/are a valid hCard
  • otherwise the entry is invalid hAtom

XMDP Profile

<dl class="profile">
 <dt>class</dt>
 <dd><p>
  <a rel="help" href="http://www.w3.org/TR/html401/struct/global.html#adef-class">
   HTML4 definition of the 'class' attribute.</a>
  This meta data profile defines some 'class' attribute values (class names) 
  and their meanings as suggested by a 
  <a href="http://www.w3.org/TR/WD-htmllink-970328#profile">
   draft of "Hypertext Links in HTML"</a>.
  <dl>
   <dt>hfeed</dt>
   <dd>
    The concept of atom:feed from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>hentry</dt>
   <dd>
    The concept of atom:entry from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>entry-title</dt>
   <dd>
    The concept of atom:title inside of an atom:entry from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>entry-content</dt>
   <dd>
    The concept of atom:content from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>entry-summary</dt>
   <dd>
    The concept of atom:summary from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>bookmark</dt>
   <dd>
    The concept of atom:link (without any "rel") with an atom:entry from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>published</dt>
   <dd>
    The concept of atom:published from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>updated</dt>
   <dd>
    The concept of atom:updated from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
   <dt>author</dt>
   <dd>
    The concept of atom:author from 
    <a href="http://www.atomenabled.org/developers/syndication/atom-format-spec.php">The Atom Syndication Format</a>, 
    constrained and modified as per the <a href="http://microformats.org/wiki/hatom">hAtom microformat spec</a>.
   </dd>
  </dl>
 </dd>
</dl>

Examples

See hatom-examples.

Examples in the wild

This section is informative.

The following sites have implemented hAtom , and thus are a great place to start for anyone looking for examples "in the wild" to try parsing, indexing, organizing etc. If your site marked up with hAtom, feel free to add it to the top of this list. Once the list grows too big, we'll make a separate wiki page.

0.1 hAtom examples

• Joomla! Melbourne User Group uses hAtom combined with hCard for articles.
• Volume - Main news page is marked up as hAtom 0.1
• Yedda - Yedda support hAtom on exploration of questions where there is also support for Atom and RSS feeds. (example)
• The West Midland Bird Club's frequently-updated What's New page, news from its Ladywalk Reserve and news from Grimley Pits — comments welcome on my talk page Andy Mabbett
• pixelsebi's repository uses hAtom 0.1 for blog posts (and hCard, hCalendar, XFN, xFolk and many more) based on manual WordPress template modifications
• Geek in the Park uses hAtom for the comments. -- by trovster
• Sarven Capadisli uses hAtom for the articles and comments -- by csarven
• fberriman.com uses hAtom 0.1 for blog posts (WordPress loop) and hCard throughout -- by Frances Berriman (Also - Implementing hAtom: The Entries Code)
• Capital University uses hAtom 0.1 to mark up the feed of latest posts by student bloggers on its home page.
• Ranting and Roaring (David Janes)
• ChunkySoup.net has redesigned using hAtom 0.1 and hCards on the entire site -- by Chris Casciano
• Sedna RSS (a feed aggregator based on SPIP, by Fil, IZO and others; GPLd sources are available at SPIP-Zone)
• Sound Advice (Benjamin Carlyle)
• Scribbish is a Typo theme which uses hAtom.
• hAtom2Atom.xsl's Changelog is published as hAtom and Atom.
• federali.st's webbed Federalist Papers are each marked up in hAtom.
• Sandbox is a theme for WordPress that uses hAtom.
  • The theme is also available to accounts on the <username>.wordpress.com hosting service. The Coworking and BarCamp blogs are examples of custom Sandbox themes.
• Strangelove is a modification of the default WordPress theme (Kubrick) with hAtom support.
  • It points to the hAtom2Atom proxy service as the link for syndication feeds.
• All plaintxt.org themes for WordPress now use hAtom. The themes, by name, are:
  • Barthelme (two-column, fluid), blog.txt (two- or three-column, elastic), http://www.plaintxt.org/themes/plaintxtblog/ plaintxtBlog] (three-column, fluid), Simplr (one column, elastic), veryplaintxt (two column, fluid)

Examples with some problems

Entries may be moved here if there's a problem with the way hAtom is used on the page concerned. If the page is yours, and you want to improve it, see the hAtom FAQ, or raise any queries on hAtom Issues or the mailing list, where people will be happy to help you.

Pre 0.1 hAtom examples

These pages conform to an older draft standard and need to be updated.

• Second p0st (Phil Pearson)

Implementations

This section is informative.

The following implementations have been developed which either generate or parse hAtom links. If you have an hAtom implementation, feel free to add it to the top of this list. Once the list grows too big, we'll make a separate wiki page.

• hAtom Creator modified from the other creators by BenWest.
• the Almost Universal Microformat Parser can extract hAtom content from webpages (example)
• the microformat-action Greasemonkey script detects hAtom content on webpages and will call the Almost Universal Microformat Parser
• hAtom2Atom.xsl transforms hAtom to Atom (as the name suggests.)
• There is now an hatom2atom proxy that uses hAtom2Atom.xsl.
• Subscribe To hAtom is a script that provides NetNewsWire 2.x users with the ability to subscribe to hAtom documents as they would any other feed. by Chris Casciano.
• Outline Classes - has GPL'ed PHP code for reading hAtom
• BoxtheWeb - supports subscribing to hAtom as a feed format

References

Normative References

• XHTML 1.0 SE
• RFC4287: The Atom Syndication Format
• hcard-parsing

Informative References

• atomenabled.org

Work in progress

This specification is a work in progress. As additional aspects are discussed, understood, and written, they will be added. There is a separate document where we are keeping our brainstorms and other explorations relating to hAtom:

• blog-post Brainstorming

Version 0.1

Version 0.1 was released 28 February 2006.

Discussions

• See blogs discussing this page.

Q&A

• If you have any questions about hAtom, check the hAtom FAQ, and if you don't find answers, add your questions!

Issues

• Please add any issues with the specification to the separate hAtom issues document.

See Also

• h-entry - latest markup spec for Atom entries in HTML
• h-feed - brainstorm/experiment for feeds in HTML
• hAtom - the draft proposal.
• hAtom Cheatsheet - hAtom properties.
• hAtom Examples, in the Wild
• hAtom Hints - help for implementors.
• hAtom Issues - problems? complaints? ideas? Put them here.
• hatom-brainstorming - active work on iterations toward the next version of hAtom
• hAtom FAQ - knowledge base.
• hAtom advocacy - encourage others to use hAtom.
• rel-enclosure - how to semantically reference enclosures (e.g. podcasts) in hAtom
• blog-post-brainstorming
• blog-post-formats
• blog-post-examples
• blog-description-format - how to describe a blog (as opposed to the individual entries, which is what we're doing here)