Map-to-map cascading behaviors

When a DITA map or map branch is referenced by another DITA map, by default certain rules apply. These rules pertain to the cascading behaviors of attributes, metadata elements, and the roles that are assigned to content , for example, the role of "Chapter" that is assigned by a <chapter> element. Attributes and elements that cascade within a map generally follow the same rules when cascading from one map to another map, but there are some exceptions and additional rules that apply.