Processing chunk="combine"

The presence of chunk="combine" instructs a processor to combine the referenced source documents for rendering purposes.

The following rules apply:

• When chunk="combine" is specified on the root element of a map, all source DITA documents that are referenced by the map are treated as one DITA document.
• When chunk="combine" is specified on a branch of a map, all source DITA documents that are referenced within that branch are treated as one DITA document.
  Note (non-normative):

  This is true regardless of whether the element that specifies @chunk refers to a topic or specifies a heading. In cases such as <topicgroup> where a grouping element specifies chunk="combine", the equivalent DITA document would be a single DITA document with a root element that groups peer topics.
• When chunk="combine" is specified on a map, map branch, or map reference, all source DITA documents that are grouped by the reference are treated as a single resource. Any additional @chunk attributes on elements within the grouping are ignored.