Special case: Some elements are intended to provide hypertext links, to other parts of the document and external resources. In such cases, when changes in the link target attributes cannot be represented, they are propagated to the element level as discussed in the next section on hypertext links.
DITA's hypertext link elements, such as the xref and link elements, use the href and/or keyref attributes to define the target of the link. And use the content of the element to define the links label.
When attribute change can not be represented, changes in hyper text links are handled specially. In this context, changes to the href or keyref attributes are propagated up to the element level; i.e. the 'A' and 'B' versions of the link element are represented as being deleted and inserted respectively, as appropriate for the selected output-format.
The full list of 'generalized' elements that are considered to be hypertext link elements are: author, fragref, image, link, publisher, source, synnoteref and xref.
Other elements, such as the topicref and data elements, also make use of the href and keyref attributes. Such elements are intended to represent more than just a hypertext link, and thus are likely to have a significant amount of content. Seeing changes within this content is important, therefore, changes in the href or keyref are not propagated to the element level in these cases.