Processing key references for navigation links and images
When a key definition is bound to a resource that is addressed by the @href or @keyref attributes, and does not specify "none" for the @linking attribute, all references to that key definition become links to the bound resource. When a key definition is not bound to a resource or specifies "none" for the @linking attribute, references to that key definition do not become links.
When a key definition has no @href value and no @keyref
value, references to that key will not result in a link, even if they do contain an
@href attribute of their own. If the key definition also does not
contain a <topicmeta> subelement, empty elements that refer to
the key (such as
<link keyref="a"/> or
href="fallback.dita"/>) are ignored.
The <object> element has additional key-referencing attributes (@archivekeyrefs, @classidkeyref, @codebasekeyref, and @datakeyref). Key names in these attributes are resolved using the same processing that is described for the normal @keyref attribute.