In asynchronous transfer mode (ATM), a traffic parameter describing the minimum number of cells per second that the network agrees to support for a given originating endpoint across a user network interface (UNI). A service descriptor for the available bit rate (ABR) service class, MCR is that rate, expressed in cells per second, at which the originating endpoint can always transmit during the course of the connection. See also ABR, ATM, cell, traffic parameter, and UNI.