Using keys for addressing
For topic references, image references, and other link relationships, resources can
        be indirectly addressed by using the @keyref attribute. For content
        reference relationships, resources can be indirectly addressed by using the
            @conkeyref attribute.
Syntax
For references to topics, maps, and non-DITA resources, the value of the
                    @keyref attribute is simply a key name (for example,
                    keyref="topic-key"). 
For references to non-topic elements within topics,
                the value of the @keyref attribute is a key name, a slash ("/"), and the ID of the target element (for
                example, keyref="topic-key/some-element-id".)
Example
This section is non-normative.
<topic id="topicid">
 <title>Example referenced topic</title>
 <body>
  <section id="section-01">Some content.</section>
 </body>
</topic>and
                this key
                definition:<map>
  <topicref keys="myexample"
    href="file.dita"
  />
</map>A cross reference of the form keyref="myexample/section-01" resolves
                to the <section> element in the topic. The key reference is
                equivalent to the URI reference
                xref="file.dita#topicid/section-01".