The format prefix (FP) is a three-bitdata field in the address field of the IPv6 protocol
. The FP data field is variable; in the case of unicast addresses, it consists of the bit combination 010. Local addresses are identified with an eight-digit bit combination (1111 1110) and multicast with 1111 1111. Address extensions to include NSAP (Network Service Access Point) and IPX addresses, Internetwork Packet Exchange (IPX), have already been provided in the address scheme.