This is the actual add/delete instruction list used to manage which unicast DLCIs belong to a multicast group tied to this circuit, encoded as a sequence of an operation code (0 for delete, 1 for add) followed by the affected DLCIs. An admin adding a new branch office to an existing broadcast group writes a string like '1:150' to add DLCI 150 as a new member without redefining the whole group, or '0:150' to remove it. For example, writing '1:100,101,102' adds three unicast DLCIs as new members of this circuit's multicast group in a single operation.