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<h1 class="title topictitle1" id="ariaid-title1"><code class="keyword markupname xmlelement"><ddhd></code></h1>
<div class="body refbody"><p class="shortdesc">A definition heading is an optional heading or title for descriptions or definitions in a
definition list.</p>
<section class="section generated" id="ddhd__content-model"><h2 class="title sectiontitle">Content model</h2>
<p class="p content-model generated">(Text | <a class="xref" href="../content-models/../base/keyword.html" title="A keyword is text or a token that has a unique value, such as a product name or unit of reusable text.">
<code class="keyword markupname xmlelement"><keyword></code>
</a> | <a class="xref" href="../content-models/../base/ph.html" title="A phrase is a small group of words that stand together as a unit, typically forming a component of a clause.">
<code class="keyword markupname xmlelement"><ph></code>
</a> | <a class="xref" href="../content-models/../base/strong.html" title="Strong text is text that is of greater importance than the surrounding text.">
<code class="keyword markupname xmlelement"><strong></code>
</a> | <a class="xref" href="../content-models/../base/em.html" title="Emphasis indicates special meaning or particular importance.">
<code class="keyword markupname xmlelement"><em></code>
</a> | <a class="xref" href="../content-models/../base/b.html" title="Bold text is text that is used to draw a reader's attention to a phrase without otherwise adding meaning to the content.">
<code class="keyword markupname xmlelement"><b></code>
</a> | <a class="xref" href="../content-models/../base/i.html" title="Italic text is text that is used to emphasize the key points in printed text, or when quoting a speaker, to show which words the speaker stressed.">
<code class="keyword markupname xmlelement"><i></code>
</a> | <a class="xref" href="../content-models/../base/line-through.html" title="A strikethrough is a typographical presentation of words with a horizontal line through their center. It can indicate that words are a mistake and not intended for inclusion, or it can be used deliberately to imply a change of thought.">
<code class="keyword markupname xmlelement"><line-through></code>
</a> | <a class="xref" href="../content-models/../base/overline.html" title="An overline is a horizontal line that is printed above a line of text, a mathematical symbol, or an illustration in a newspaper or journal.">
<code class="keyword markupname xmlelement"><overline></code>
</a> | <a class="xref" href="../content-models/../base/sup.html" title="A superscript is text that is printed above the line. It is frequently used in chemical and mathematical formulas.">
<code class="keyword markupname xmlelement"><sup></code>
</a> | <a class="xref" href="../content-models/../base/sub.html" title="A subscript is text that is printed below the line. It is frequently used in chemical and mathematical formulas.">
<code class="keyword markupname xmlelement"><sub></code>
</a> | <a class="xref" href="../content-models/../base/tt.html" title="Teletype text is text that is displayed on a fixed-width display such as a teletype, text-only screen, or line printer.">
<code class="keyword markupname xmlelement"><tt></code>
</a> | <a class="xref" href="../content-models/../base/u.html" title="An underline, also called an underscore, is a line immediately below a portion of text.">
<code class="keyword markupname xmlelement"><u></code>
</a> | <a class="xref" href="../content-models/../base/q.html" title="A quotation is a small group of words that is taken from a text or speech and repeated by someone other than the original author or speaker.">
<code class="keyword markupname xmlelement"><q></code>
</a> | <a class="xref" href="../content-models/../base/term.html" title="A term is a word or phrase that has specific meanings in certain contexts. It might have or require extended definitions or explanations.">
<code class="keyword markupname xmlelement"><term></code>
</a> | <a class="xref" href="../content-models/../base/text.html" title="The text element is a container for text. It does not have any associated semantics.">
<code class="keyword markupname xmlelement"><text></code>
</a> | <a class="xref" href="../content-models/../base/tm.html" title="A trademark is a term or phrase that is trademarked. Trademarks include registered trademarks, service marks, slogans, and logos.">
<code class="keyword markupname xmlelement"><tm></code>
</a> | <a class="xref" href="../content-models/../base/cite.html" title="A citation is the name or the title of a bibliographic resource, for example, a document, online article, or instructional video.">
<code class="keyword markupname xmlelement"><cite></code>
</a> | <a class="xref" href="../content-models/../base/data.html" title="Data is a generic component that represents metadata within a topic or map. Complex metadata is represented by nested data structures.">
<code class="keyword markupname xmlelement"><data></code>
</a> | <a class="xref" href="../content-models/../base/sort-as.html" title="The sort-as element can be used to specify an effective sort phrase when the base sort phrase is not appropriate for sorting, for example, Japanese characters. This element prepends text to the base sort phrase in order to construct an effective sort phrase.">
<code class="keyword markupname xmlelement"><sort-as></code>
</a> | <a class="xref" href="../content-models/../base/draft-comment.html" title="A draft comment is content that is intended for review and discussion, such as questions, comments, and notes to reviewers. This content is not intended to be included in production output.">
<code class="keyword markupname xmlelement"><draft-comment></code>
</a> | <a class="xref" href="../content-models/../base/foreign.html" title="Foreign content is non-DITA content, such as MathML, SVG, or Rich Text Format (RTF).">
<code class="keyword markupname xmlelement"><foreign></code>
</a> | <a class="xref" href="../content-models/../base/required-cleanup.html" title="Required cleanup sections are placeholders for migrated elements that cannot be appropriately tagged without manual intervention, or for content that must be cleaned up before publishing.">
<code class="keyword markupname xmlelement"><required-cleanup></code>
</a> | <a class="xref" href="../content-models/../base/image.html" title="An image is a reference to artwork that is stored outside of the content.">
<code class="keyword markupname xmlelement"><image></code>
</a>)*</p>
<p class="p content-model generated">Contained by</p>
<p class="p content-model generated">
<a class="xref" href="../content-models/../base/dlhead.html" title="A definition list heading is a group that contains a heading for items and a heading for definitions within the list.">
<code class="keyword markupname xmlelement"><dlhead></code>
</a>
</p>
<div class="p content-model-prose generated">Zero or more of the following<ul class="ul">
<li class="li">Text</li>
<li class="li">
<a class="xref" href="../content-models/../base/b.html" title="Bold text is text that is used to draw a reader's attention to a phrase without otherwise adding meaning to the content.">
<code class="keyword markupname xmlelement"><b></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/cite.html" title="A citation is the name or the title of a bibliographic resource, for example, a document, online article, or instructional video.">
<code class="keyword markupname xmlelement"><cite></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/data.html" title="Data is a generic component that represents metadata within a topic or map. Complex metadata is represented by nested data structures.">
<code class="keyword markupname xmlelement"><data></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/draft-comment.html" title="A draft comment is content that is intended for review and discussion, such as questions, comments, and notes to reviewers. This content is not intended to be included in production output.">
<code class="keyword markupname xmlelement"><draft-comment></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/em.html" title="Emphasis indicates special meaning or particular importance.">
<code class="keyword markupname xmlelement"><em></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/foreign.html" title="Foreign content is non-DITA content, such as MathML, SVG, or Rich Text Format (RTF).">
<code class="keyword markupname xmlelement"><foreign></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/i.html" title="Italic text is text that is used to emphasize the key points in printed text, or when quoting a speaker, to show which words the speaker stressed.">
<code class="keyword markupname xmlelement"><i></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/image.html" title="An image is a reference to artwork that is stored outside of the content.">
<code class="keyword markupname xmlelement"><image></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/keyword.html" title="A keyword is text or a token that has a unique value, such as a product name or unit of reusable text.">
<code class="keyword markupname xmlelement"><keyword></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/line-through.html" title="A strikethrough is a typographical presentation of words with a horizontal line through their center. It can indicate that words are a mistake and not intended for inclusion, or it can be used deliberately to imply a change of thought.">
<code class="keyword markupname xmlelement"><line-through></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/overline.html" title="An overline is a horizontal line that is printed above a line of text, a mathematical symbol, or an illustration in a newspaper or journal.">
<code class="keyword markupname xmlelement"><overline></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/ph.html" title="A phrase is a small group of words that stand together as a unit, typically forming a component of a clause.">
<code class="keyword markupname xmlelement"><ph></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/q.html" title="A quotation is a small group of words that is taken from a text or speech and repeated by someone other than the original author or speaker.">
<code class="keyword markupname xmlelement"><q></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/required-cleanup.html" title="Required cleanup sections are placeholders for migrated elements that cannot be appropriately tagged without manual intervention, or for content that must be cleaned up before publishing.">
<code class="keyword markupname xmlelement"><required-cleanup></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/sort-as.html" title="The sort-as element can be used to specify an effective sort phrase when the base sort phrase is not appropriate for sorting, for example, Japanese characters. This element prepends text to the base sort phrase in order to construct an effective sort phrase.">
<code class="keyword markupname xmlelement"><sort-as></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/strong.html" title="Strong text is text that is of greater importance than the surrounding text.">
<code class="keyword markupname xmlelement"><strong></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/sub.html" title="A subscript is text that is printed below the line. It is frequently used in chemical and mathematical formulas.">
<code class="keyword markupname xmlelement"><sub></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/sup.html" title="A superscript is text that is printed above the line. It is frequently used in chemical and mathematical formulas.">
<code class="keyword markupname xmlelement"><sup></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/term.html" title="A term is a word or phrase that has specific meanings in certain contexts. It might have or require extended definitions or explanations.">
<code class="keyword markupname xmlelement"><term></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/text.html" title="The text element is a container for text. It does not have any associated semantics.">
<code class="keyword markupname xmlelement"><text></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/tm.html" title="A trademark is a term or phrase that is trademarked. Trademarks include registered trademarks, service marks, slogans, and logos.">
<code class="keyword markupname xmlelement"><tm></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/tt.html" title="Teletype text is text that is displayed on a fixed-width display such as a teletype, text-only screen, or line printer.">
<code class="keyword markupname xmlelement"><tt></code>
</a>
</li>
<li class="li">
<a class="xref" href="../content-models/../base/u.html" title="An underline, also called an underscore, is a line immediately below a portion of text.">
<code class="keyword markupname xmlelement"><u></code>
</a>
</li>
</ul>
</div>
<p class="p content-model-prose generated">Contained by</p>
<ul class="ul content-model-prose contained-by-list generated">
<li class="li">
<a class="xref" href="../content-models/../base/dlhead.html" title="A definition list heading is a group that contains a heading for items and a heading for definitions within the list.">
<code class="keyword markupname xmlelement"><dlhead></code>
</a>
</li>
</ul>
</section>
<section class="section generated" id="ddhd__inheritance"><h2 class="title sectiontitle">Inheritance</h2>
<p class="p inheritance">- topic/ddhd </p>
<p class="p inheritance-prose">The <code class="keyword markupname xmlelement"><ddhd></code> element is a base element type. It is defined in the topic module.</p>
</section> <section class="section" id="ddhd__attributes"><h2 class="title sectiontitle">Attributes</h2>
<p class="p attributes-prose">The following attributes are
available on this element: <span class="ph"><a class="xref" href="../../common/../langRef/attributes/universalAttributes.html" title="Universal attributes include: audience, base, class, conaction, conkeyref, conref, conrefend, deliveryTarget, dir, id, importance, otherprops, outputclass, platform, product, props, rev, status, translate, and xml:lang">universal
attributes</a></span>.</p>
<p class="p inlined-attributes">The following attributes are available on this element: <a class="xref" href="../../common/../langRef/attributes/universalAttributes.html" title="Universal attributes include: audience, base, class, conaction, conkeyref, conref, conrefend, deliveryTarget, dir, id, importance, otherprops, outputclass, platform, product, props, rev, status, translate, and xml:lang">universal
attributes</a>.</p></section>
<div class="example non-normative" id="ddhd__example"><h2 class="title sectiontitle">Example</h2><p class="non-normative-label">This section is non-normative.</p>
<p style="color:red;" class="p">See <a class="xref" href="dlhead.html#dlhead__example"><code class="keyword markupname xmlelement"><dlhead></code></a>.</p></div>
</div>
<nav role="navigation" class="related-links"><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../../langRef/containers/body-elements.html" title="The body elements support the most common types of content for topics: paragraphs, lists, phrases, figures, and other common document components.">Body elements</a></div></div></nav><aside class="section-toc" role="aside"><h2>In this section</h2><ul><li><a href="#ddhd__content-model">Content model</a></li><li><a href="#ddhd__inheritance">Inheritance</a></li><li><a href="#ddhd__attributes">Attributes</a></li><li><a href="#ddhd__example">Example</a></li></ul></aside></article></main>