This read-write enumeration (enable(1), disable(2)), added for the FRSM12 card, adds a channel-level loopback toward the port side when enabled, and while the connection is in this loopback state its FrChanCnfGrpEntry configuration variables cannot be modified; it does not apply to MGX Release 1.x. An administrator enables this to test a specific channel toward the port side, but must remember configuration changes are locked out during that test. For example, an engineer troubleshooting a single channel on an FRSM12 port would enable frChanLocalLpbkEnable to loop that channel, but would first finish any needed configuration changes since the connection's config MIB becomes read-only while looped.