This read-only gauge reports the current number of distinct users, as defined by the grouping settings of the firewall's traffic-shaping pipes, being actively tracked at each 1/20th-of-a-second time slice, which the description specifically notes is not the same as counting open connections. Admins use it to gauge how many distinct traffic-shaping user buckets are actively passing traffic at any instant, for QoS capacity planning. For example, a pipe consistently near its configured per-user limit with a high clvPipeUsers count would tell the admin many simultaneous users are competing for that pipe's bandwidth.