This read-write bitmap defines which ports are eligible to participate in user-based VLAN assignment, where an authenticated user's VLAN membership follows their identity rather than the port's static configuration. An administrator scopes this to the access ports where roaming or shared workstations need per-user VLAN placement. For example, hot-desking areas where any employee might plug in would be included in this bitmap so each user lands on their correct department VLAN regardless of desk.