Question: What is the requirement for Diameter NASREQ (IETF RFC 7155) AVPs marked with "M" in the Gmb interface?
Option 1: They are mandatory and must be supported for compliance.
Option 2: They are optional but recommended for better performance.
Option 3: They are not required for being compliant with the current specification.
Option 4: They are only applicable to specific use cases.
Explanation: According to the text, Diameter NASREQ (IETF RFC 7155) AVPs marked with "M" are not required for compliance with the current specification. This means that even if an AVP is marked as mandatory in the IETF RFC 7155, it is still not necessary to support it for compliance with the Gmb interface.