Nortel Networks Microsoft This draft proposes a standardized set of sub-application (SAPP) identifiers for real-time application, namely, audio, video and telephony (voice and fax) applications. These SAPP identifiers are used in the RSVP Identity Policy Element in the Policy Data Object [RFC 2750]. The standardized set of SAPP identifiers proposed in this draft facilitate the deployment of policy-enabled, real-time applications.