Examples: Key definition
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".