B.6 DITA module and shell implementation reference
(Non-normative) The DITA standard defines a set of base types and vocabulary modules
and a set of specialized map types, topic types, and domains.
B.6.1 DTD organization
(Non-normative) The OASIS DITA document types are implemented with a set of DTD modules. Some of these modules are used by every DITA document type, others are only used by topics or by maps, and some are only used in specific specializations.
B.6.2 XML schema organization
(Non-normative) The OASIS DITA document types are implemented with a set of schema modules. Some of these modules are used by every DITA schema document, others are only used by topics or by maps, and some are only used in specific specializations.