In asynchronous transfer mode (ATM), a class of traffic that requires access to time slots at regular and precise intervals.Traffic parameters include peak cell rate (PCR) and cell delay variation tolerance (CDVT). Quality of Service (QoS) parameters include cell delay variation (CDV), cell transfer delay (CTD), and cell loss ratio (CLR). Real-time, uncompressed voice and video are examples of CBR traffic. ATM also defines available bit rate (ABR), non real-time Variable Bit Rate (nrt-VBR), realtime Variable Bit Rate (rt-VBR), unspecified bit rate (UBR), and variable bit rate (VBR) traffic classes. See also ABR, ATM, compression, CDVT, CTD, nrt-VBR, PCR, QoS, rt-VBR, time slot, traffic, UBR, and VBR.