Content referencing (conref) is a convenient mechanism for reuse of content fragments. A fragment of content may be included from another location. To do so, the top element to be included is repeated at the location that will receive the inclusion. Instead of the usual attributes or content, the referencing element is given a conref attribute that specifies the location of the referenced element.

The element containing the content reference acts as a placeholder for the referenced element. The identifier for the referenced element must be either absolute or resolvable in the context of the referencing element. (See Identity attribute for the details on identifiers.)

More formally, the DITA conref attribute can be considered a transclusion mechanism. In that respect, conref is similar to XInclude as well as HyTime value references. DITA differs from these mechanisms, however, by comparing the constraints of each context to ensure the ongoing validity of the replacement content in its new context. In other words, conref validity does not apply simply to the current content at the time of replacement, but to the ranges of possible content given the constraints of the two document types. A valid conref processor does not allow the resolution of a reuse relationship that could be rendered invalid under the rules of either the reused or reusing content.

The architectural specification describes content referencing at:

• http://docs.oasis-open.org/dita/v1.0/archspec/conref.html.