This read-write setting designates whether this end of the connection acts as master or slave, or is unknown, a role used internally by the PXM switch platform module. It affects which end has authority for certain connection-management decisions, such as who initiates re-signaling for an SPVC. An admin configuring both ends of a connection would typically set one end's bbChanMaster to master(1) and the other to slave(2) to establish a clear authority relationship.