DITA maps are documents that organize topics and
other resources into structured collections of information.
DITA maps specify hierarchy and the relationships among the
topics; they also provide the contexts in which
keys are defined and resolved. DITA maps SHOULD have .ditamap as
the file extension.
DITA maps have unique attributes that are designed to control the
way that relationships are interpreted for different output purposes. In
addition, DITA maps share many metadata and linking attributes with DITA