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

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.

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.
Use the most accurately precise semantic XHTML building block for each object etc.
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>).
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.
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 that 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. required. 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 is 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 with class name author
- otherwise the page 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:updatedfrom 
    <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.

Ranting and Roaring (David Janes)
Second p0st (Phil Pearson)
Sound Advice (Benjamin Carlyle)
Sedna RSS (a feed aggregator based on SPIP, by Fil, IZO and others; GPLd sources are available at SPIP-Zone)
hAtom2Atom.xsl’s Changelog is published as hAtom and Atom.

Implementations