This value is the third reverse traffic descriptor parameter (typically reverse maximum burst size) for this failed call, per the description, completing the reverse-direction traffic contract alongside svcAtmFailedCallAtmRTfdParam1 and Param2. An unusually large value here relative to this port's reverse buffering capacity would be consistent with a burst-tolerance-driven admission rejection specific to the return path, distinct from an average-rate rejection. This is a detail an admin would pull up only after the cause code and QoS class fields point toward a bandwidth-related failure.