Base elements include the core DITA topic and map elements
that are the building blocks for other specializations as well as
several basic specializations that are not applicable to a specific
information domain.
3.1.1 Topic elements
The base topic elements include elements that make up the core building blocks of the DITA topic, such as topic, body, and related-links, as well as elements like <p> and <ph> that are used in many topic specializations. Some of these elements are also available inside the <topicmeta> map element.
3.1.2 Map elements
Map elements include the core components of DITA maps, such as <topicref> and <reltable>, as well as general purpose map specializations in the map group domain.
3.1.3 Metadata elements
Metadata elements include information that is located within the <topicmeta> element (in maps) or <prolog> element (in topics), as well as indexing elements that can be placed in additional locations within topic content.
3.1.4 Domain elements
General purpose domains are not specific to any type of information, such as the hazard statement domain that provides elements for describing hazardous situations.
3.1.5 Classification elements
Classification elements support managing metadata. Those in the Subject Scheme map are used to define controlled values, and to bind them to DITA attributes as enumerations. Those declared in the classification domain are used in other maps to classify content according to the scheme.
3.1.6 Specialization elements
Several DITA elements exist either for architectural reasons or for support of specialized markup yet to be designed. Although there is little need to use these elements unless you are directed to, some of them, such as <state>, can be used if your content makes use of these semantic distinctions. For example, a discussion of signals on a gate of an integrated logic circuit might use the state element to represent either on or off conditions of that gate.
3.1.8 DITAVAL elements
A conditional processing profile (DITAVAL file) is used to identify which values are to be used for conditional processing during a particular output, build, or some other purpose. The profile should have an extension of .ditaval.