This is obtained from the Group ID field as received via the maintenance protocol used for VC setup, is zero if not used, and reads 0xFFFF if the object is yet to be defined by the VC maintenance protocol. This is the read-only mirror of cpwVcLocalGroupID but learned from the remote PE rather than configured locally, and the MIB calls out 0xFFFF as a specific placeholder meaning the remote signaling protocol has not yet communicated a real group ID, which an admin should distinguish from a genuine, intentional group ID of 0. For example, seeing this value at 0xFFFF shortly after a pseudowire first comes up would tell the admin the remote PE's group ID simply has not been received yet, rather than that the remote end deliberately configured no group membership.