Examples: Key definition

The <topicref> element, and any specialization of <topicref> that allows the @keys attribute, can be used to define keys.

In the following example, a <topicref> element is used to define a key; the <topicref> element also contributes to the navigation structure.

<map>
  <!--... -->
  <topicref keys="apple-definition" href="apple-gloss-en-US.dita" />
  <!--... -->
</map>

The presence of the @keys attribute does not affect how the <topicref> element is processed.

In the following example, a <keydef> element is used to define a key.

<map>
  <!--... -->
  <keydef keys="apple-definition" href="apple-gloss-en-US.dita"/>
  <!--... -->
</map>

Because the <keydef> element sets the default value of the @processing-role attribute to "resource-only", the key definition does not contribute to the map navigation structure; it only serves as a key definition for the key name "apple-definition".