z/OS XML System Services will handle internal DTDs for the purpose of processing entity declarations and default attribute value definitions. It only processes entity declarations and default attribute values from the internal DTD. Processing instructions that fall within the internal DTD will be returned to the caller, but no other text from the DTD will be processed. The z/OS XML parser will return a DTD record in the parsed data stream that contains the name of the root element, plus the system and public literals that make up the identifier of any external subset. The content of the internal subset is not returned to the caller.