The base DITA element and attribute types may be extended through the creation of
new vocabulary modules that define specializations of more-general types.
To be extensible and backward compatible, DITA requires that a DTD implementation
of
structural and domain specialization modules conform to well-defined implementation
(coding)
requirements.
To be extensible and backward compatible, DITA requires that an XSD implementation
of
structural and domain specialization modules conform to well-defined implementation
(coding)
requirements.