This defines the groups of user priority bits mapped into this VC, with each bit set indicating that user priority is assigned to this VC, allowing different PSN classes of service to be based on user 802.1p marking without requiring multiple-COS support elsewhere. This bitmask is the mechanism for mapping specific 802.1p priority bits from customer Ethernet frames onto this particular pseudowire, useful when a single physical port is split across several VCs by priority so that, for example, voice-tagged frames ride a different, better-treated pseudowire than best-effort traffic sharing the same access port. For example, setting only the pri101 and pri110 bits on a voice-dedicated VC while a separate VC on the same port carries the pri000 bit for best-effort traffic implements priority-based traffic separation across two pseudowires sharing one physical Ethernet port.