The Darwin Information Typing Architecture (DITA) is an XML-based, end-to-end architecture for authoring, producing, and delivering technical information. This architecture consists of a set of design principles for creating “information-typed” modules at a topic level and for using that content in delivery modes such as online help, product support portals on the Web, and printed manuals. DITA’s design consists of a set of matching design and code modules, based on information types and domains. When you need a real difference in output (not just a subset of allowed input), you can use DITA customization to override the default output without affecting portability or interchange. When you require a difference in output that reflects a real difference in input, or you want to make changes to your design for the sake of increased consistency or descriptiveness (regardless of output), you can use DITA specialization to define new information types or new domains.
But see the author package.