2.1.1 [XML] Section 4.7, Notation Declarations
XML processors MUST provide applications with the name and external identifier(s) of any notation declared and referred to in an attribute value, attribute definition, or entity declaration. They MAY additionally resolve the external identifier into the system identifier, file name, or other information needed to allow the application to call a processor for data in the notation described. (It is not an error, however, for XML documents to declare and refer to notations for which notation-specific applications are not available on the system where the XML processor or application is running.)
IE9 Mode, IE10 Mode, IE11 Mode, and EdgeHTML Mode (All Versions)
Names and external identifiers of declared notations are not provided to applications.