Content can be chunked (divided or merged into new output documents) in different ways for the purposes of delivering content and navigation. For example, content best authored as a set of separate topics might need to be delivered as a single Web page. A map author can use the @chunk attribute to split up multi-topic documents into component topics or to combine multiple topics into a single document as part of output processing.

The @chunk attribute is commonly used for the following use cases.

Reuse of a nested topic
A content provider creates a set of topics as a single document. Another user wants to incorporate only one of the nested topics from the document. The new user can reference the nested topic from a DITA map, using the @chunk attribute to specify that the topic should be produced in its own document.
Identification of a set of topics as a unit
A curriculum developer wants to compose a lesson for a SCORM LMS (Learning Management System) from a set of topics without constraining reuse of those topics. The LMS can save and restore the learner's progress through the lesson if the lesson is identified as a referenceable unit. The curriculum developer defines the collection of topics with a DITA map, using the @chunk attribute to identify the learning module as a unit before generating the SCORM manifest.