https://microformats.org/wiki/api.php?action=feedcontributions&feedformat=atom&user=HeribertMicroformats Wiki - User contributions [en]2026-04-15T10:14:36ZUser contributionsMediaWiki 1.38.4https://microformats.org/wiki/index.php?title=dfn-design-pattern&diff=37662dfn-design-pattern2009-01-14T14:23:35Z<p>Heribert: /* Usage in the wild */</p>
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<div>=Dfn design pattern=<br />
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<strong>Important</strong>: this is currently a proposal: it is <em>not</em> a finalised design pattern.<br />
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This page is intended for discussion and exploration of a design pattern to complement the [[abbr-design-pattern|abbr design pattern]] while addressing the [[abbr-design-pattern-issues|abbr design pattern issues]], particularly the [[accessibility-issues#abbr-design-pattern|accessibility issues]].<br />
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__TOC__<br />
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==Purpose==<br />
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The [[abbr-design-pattern|abbr design pattern]] is used in several microformats to enclose standardised data such as the [[datetime-design-pattern|datetime design pattern]] in the <code>title</code> attribute. However some [[assistive-technology|assistive technology]] will expose this data directly to the user, which is often undesirable.<br />
See also [[assistive-technology-abbr-results|assistive technology abbr results]].<br />
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This problem arises because the <code>title</code> attribute has a different semantic meaning when it is attached to an <code>abbr</code> or <code>acronym</code> than it does on other elements. Usually [http://www.w3.org/TR/html4/struct/global.html#h-7.4.3 the <code>title</code> attribute] is used to provide provide advisory information. But for <code>abbr</code> or <code>acronym</code> the <code>title</code> is used to provide an expanded form of the text contained between the opening and closing tags. This is why the <code>abbr</code> element was chosen to contain datetime information: the ISO format is an expanded form of the human-readable text contained within the element. Because screen readers can be configured to treat <code>abbr</code> and <code>acronym</code> elements as special cases, the <code>title</code> attribute is sometimes read aloud.<br />
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==Proposal==<br />
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Rather than expand the [[abbr-design-pattern|abbr design pattern]] to any element (or to a semantically neutral element such as <code>span</code>), it would be better to use an element that has semantic value but which isn't treated as a special case by assistive technology.<br />
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===dfn===<br />
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The [http://www.w3.org/TR/html4/struct/text.html#h-9.2.1 dfn element] indicates the defining instance of the enclosed term. This element is not widely used but where it used, it is often used in a similar way to the <code>abbr</code> element. Although the <code>title</code> is not required for the <code>dfn</code> element, it is often used to provide expanded information.<br />
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The semantic meaning of <code>dfn</code>, as it is currently used, is potentially similar enough to <code>abbr</code> element to allow it to be used as an alternative:<br />
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<pre><nowiki><br />
<abbr class="dtstart" title="2007-08-16T22:00:00">10pm on August 16th</abbr><br />
<dfn class="dtstart" title="2007-08-16T22:00:00">10pm on August 16th</dfn><br />
</nowiki></pre><br />
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==Issues==<br />
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===Semantics===<br />
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The <code>dfn</code> is <em>not</em> intended for definitions; it is intended for defining instances. Does this mean that it must always be used for the first instance of a term (such as a date)?<br />
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Is the <code>dfn</code> element equally appropriate as the <code>abbr</code> for information such as datetimes and geo or is this stretching the semantic meaning of the element beyond a reasonable limit?<br />
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====HTML5====<br />
In HTML5, the [http://www.w3.org/html/wg/html5/#the-dfn|DFN element semantics] have completely changed and would be incompatable with this pattern.<br />
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===Parsers===<br />
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Existing microformats parsers (such as the Operator extension to Firefox) would need to be updated to handle this proposed alternative to the abbr design pattern. However, this is true of any proposed alternatives.<br />
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===Complexity===<br />
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Microformats are intended to be easy to publish. The number of design patterns should be kept to a minimum. Every new design pattern is potentially a new barrier to entry for publishers.<br />
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===Assistive Technology===<br />
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The proposed dfn design pattern assumes that screen readers don't treat <code>dfn</code> as a special case like <code>abbr</code> or <code>acronym</code>. Is this actually the case? Please note results of testing on that item in the [[assistive-technology-abbr-results|assistive technology results]] page.<br />
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===Usage in the wild===<br />
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This design pattern is built on the assumption that, although the <code>dfn</code> is not widely used, where it used, it is most often used in conjunction with the <code>title</code> attribute. Please document examples and references here:<br />
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* [http://juicystudio.com/article/jargon-busting-with-the-definition-element.php Juicy Studios: Jargon Busting with the Definition Element]<br />
* [http://alistapart.com/articles/hattrick A List Apart: The Accessibility Hat Trick: Getting Abbreviations Right]<br />
* [http://www.arthrogryposis.de/iga/iga-ev/schirmherr German Arthrogryposis Support Group] (medical terms checked against a glossary)<br />
* ...<br />
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==Alternatives==<br />
*[[title-trigger]]<br />
*...<br />
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==See Also==<br />
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* [[abbr-design-pattern|abbr design pattern]]<br />
* [[abbr-design-pattern-issues|abbr design pattern issues]]<br />
* [[accessibility-issues#abbr-design-pattern|accessibility issues]]<br />
* [[assistive-technology-abbr-results|assistive technology abbr results]]<br />
* [[datetime-design-pattern|datetime design pattern]]</div>Heribert