Page "Document Type Definition" Paragraph 41

Note also that even in validating SGML or XML 1. 0 or XML 1. 1 parsers, the external entities referenced by an FPI and / or URI in declared notations are not retrieved automatically by the parsers themselves.

Instead, these parsers just provide to the application the parsed FPI and / or URI associated to the notations found in the parsed SGML or XML document, and with a facility for a dictionary containing all notation names declared in the DTD ; these validating parsers will also check the uniqueness of notation name declarations, and will report a validation error if some notation names are used anywhere in the DTD or in the document body but not declared: