This object specifies the VLAN tag value used on the control SAP associated with a Maintenance End Point (MEP) in the CFM configuration, restricted here to either 0 or the range 512 through 768. An administrator sets this when the MEP's OAM control traffic needs to be carried on a specific VLAN tag from that constrained range, distinct from the service's regular data traffic. For example, setting tnDot1agCfmMepControlSapTag to 600 directs that MEP's CFM control messages onto VLAN 600, a value within the platform's allowed control-tag range.