Xref, or cross-reference, is a link from within the body of a topic to any local or external target.
Figure 1. Xref in Serna.
Target location
Local elements
Local topics
External elements
External topics
DITA documents
Non-DITA documents
External sources, such as documents on the web
Attributes
The href attribute provides the location of the target.
The format attribute identifies the format of the target: dita, html, pdf or ditamap.
The scope attribute identifies the closeness of the relationship between the current document and the target: local, peer or external.