This read-write TruthValue enables an immediate-leave mode on this VLAN, where the switch stops forwarding multicast traffic to a port as soon as it sees a leave message, without waiting through the normal group-specific query confirmation process. An administrator enables this on VLANs with only one multicast receiver per port, where there's no risk of prematurely cutting off other listeners sharing that port. For example, enabling rlIgmpMldSnoopVlanIsImmediateLeave on a VLAN where each port connects to exactly one set-top box lets the switch stop a channel's multicast stream the instant that box leaves, without the usual confirmation delay.