dfn
elementdfn
element descendants.title
attribute has special semantics on this element.HTMLElement
.The dfn
element represents the defining
instance of a term. The paragraph,
description list group, or section that is the nearest
ancestor of the dfn
element must also contain the
definition(s) for the term given
by the dfn
element.
Defining term: If the dfn
element has a
title
attribute, then
the exact value of that attribute is the term being defined.
Otherwise, if it contains exactly one element child node and no
child Text
nodes, and that child
element is an abbr
element with a title
attribute, then the exact value
of that attribute is the term being defined. Otherwise, it
is the exact textContent
of the dfn
element that gives the term being defined.
If the title
attribute of the
dfn
element is present, then it must contain only the
term being defined.
The title
attribute
of ancestor elements does not affect dfn
elements.
An a
element that links to a dfn
element represents an instance of the term defined by the
dfn
element.
In the following fragment, the term "Garage Door Opener" is first defined in the first paragraph, then used in the second. In both cases, its abbreviation is what is actually displayed.
<p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn> is a device that allows off-world teams to open the iris.</p> <!-- ... later in the document: --> <p>Teal'c activated his <abbr title="Garage Door Opener">GDO</abbr> and so Hammond ordered the iris to be opened.</p>
With the addition of an a
element, the reference
can be made explicit:
<p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn> is a device that allows off-world teams to open the iris.</p> <!-- ... later in the document: --> <p>Teal'c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a> and so Hammond ordered the iris to be opened.</p>