This read-create value identifies the ATM QoS class for this traffic descriptor among ubr (unspecified bit rate, best effort), cbr (constant bit rate), vbrAudioVideo, vbrConnData, and vbrConnlessData, defaulting to ubr, and per the source DESCRIPTION matches the standard ATM Mgt MIB's atmTrafficDescrQoSClass object but with textual enumerations instead of raw numbers. An admin sets it to determine what traffic-shaping behavior and bandwidth guarantee a virtual circuit using this descriptor receives. For example, an admin provisioning a circuit for voice traffic would set this to cbr(1) to get the guaranteed, constant bit-rate behavior voice traffic typically requires.