This read-write octet string is the actual bitmap of which individual SMDS addresses are members of this port's screening policy, with the encoding using the first byte as an add or delete operation code, 1 for delete and 2 for add, followed by a bitmap where each bit position corresponds to a specific screen member ID. An admin writes to this to incrementally add or remove specific SMDS addresses from the allowed, or blocked, set without having to re-specify the whole membership list from scratch. For example, an admin adding a new permitted peer address writes a SET request whose first byte is 2 for add, followed by a bitmap with that peer's corresponding bit turned on, leaving all other membership bits untouched by that particular operation.