This is the running total of data units received by the interworking function on this interface, where the specific unit (packets, frames, or bytes) is defined by the companion receive-unit object. Administrators use it as the primary receive-traffic counter for this interworking interface, tracking it over time to gauge throughput or detect a stalled data flow. If this counter stops incrementing while the interface is expected to be actively passing traffic, an admin would suspect a receive-side problem on the IWF.