This value defines the set of switch ports (encoded as a bitmap, one bit per port) that belong to a given VLAN-translation group, as the writable column of a table indexed by the group ID, used to organize which physical ports share the same VLAN ID mapping rules. A network administrator sets this when building a group of ports that should all have their tagged VLAN IDs translated the same way, for example grouping several customer-facing ports together. For example, setting this to a bitmap covering ports 1 through 4 would add those four ports to the group whose translated VLAN mapping is defined elsewhere in the table.