You can override features of a built-in or previously defined DITA content model without creating a specialized type, by providing a content-model configuration file that lists only the differences from the original model. You can use this method to modify maps as well as topic types; see §41.7.4 Overriding declarations in a DITA map content model.
To override settings in a DITA content model:
[Topic]
; TopicDerivation = name of type from which it is derived,
; either one of the defined types (topic, concept, task,
; reference, glossary, or map) or another specialized type
; for which an .ini is available.
TopicDerivation = topictype
TopicDerivation can be any of the built-in topic types (topic, concept, task, reference, glossary, map, or bookmap), or any specialized type for which a content-model configuration file named DITAtopictype.ini is available (see §41.7 Specializing or modifying DITA topic types). Do not use TopicDerivation in content-model configuration files generated by dtd2ini; those content models are always complete.
For example, to change the PUBLIC declaration for glossary topics (to conform to XMetaL requirements) without changing the declaration for any other topic type:
[Topic]
ModelName = glossary
TopicDerivation = glossary
TopicRoot = glossentry
PrologDType = "-//OASIS//DTD DITA Composite//EN"
PrologDTD = "ditabase.dtd"
In your project configuration file:
[DITAContentModels]
glossary = my modified model for XMetaL (a comment)