The filter mask for this station. The semantics of the filter mask depend on the type of filter. For a source filter, the mask gives the ports that are allowed to receive frames from the filtered address. For a destination filter, the mask gives the ports that are forced to receive frames destined to the filtered address. Each octet within the value of this object specifies a set of eight ports, with the first octet specifying ports 1 through 8, the second octet specifying ports 9 through 16 (if available), etc. Within each octet, the most significant bit represents the lowest numbered port, and the least significant bit represents the highest numbered port. Thus, each port of the switch is represented by a single bit within the value of this object. If that bit has a value of '1' then that port is included in the set of ports; the port is not included if its bit has a value of '0'.