This value sets the ATM traffic service category, options like constant bit rate (CBR), real-time or non-real-time variable bit rate (VBR), available bit rate (ABR), or unspecified bit rate (UBR), that applies to any circuits configured to use this particular ATM profile. Administrators pick a service category based on the kind of traffic the circuit will carry, for example CBR for latency-sensitive voice or video circuits versus UBR for best-effort data. For instance, setting this to rtVbr on a profile used for a video conferencing circuit reserves bandwidth with real-time delivery guarantees appropriate for that traffic.