DITA provides some attributes to provide type information to processors
instead of qualifications or properties of content.
Ordinarily, architectural attributes don't appear in the source files for
document instances. Instead, architectural attributes appear in document instances
through defaults set in the DTD or Schema declaration. This practice ensures
that the creation of document instances cannot produce invalid values for
the architectural attributes. These attributes are as follows:
- class
- This attribute identifies the specialization module for the element type
as well as the ancestor element types and the specialization modules to which
they belong. Every DITA element has a class attribute.
- domains
- This attribute identifies the domain specialization modules used in a
topic and, for each domains module, its module dependencies. Every topic and
map element has a domains attribute.
- DITAArchVersion
- This attribute identifies the version of the DITA architecture used by
the DTD or schema.Every topic and map element has a DITAArchVersion attribute.
The attribute is declared in a DITA namespace to allow namespace-sensitive
tools to detect DITA markup.
To make the document instance usable without the DTD or Schema declaration,
a normalization process can instill the architectural attributes in the document
instance.