This object holds the 8-byte Fibre Channel LUN identifier that restricts an Inter-VSAN Routing (IVR) zone member to one specific LUN on a target, rather than exposing every LUN the target presents; a zero-length value means no LUN-level zoning is configured for that member. A SAN admin cares because this is what actually enforces LUN-level access control across VSAN boundaries, and leaving it empty is what lets a host reach LUNs it shouldn't. For example, an admin limiting a Windows host in VSAN 10 to only LUN 0x0002000000000000 on a cross-VSAN array would populate this field with that 8-byte value rather than leaving it zero-length.