The IP multicast group address which, when combined with alaPimGroupMappingGrpPrefixLength, gives the group prefix for this mapping. The InetAddressType is given by the alaPimGroupMappingAddressType object. This address object is only significant up to alaPimGroupMappingGrpPrefixLength bits. The remainder of the address bits are zero. This is especially important for this index field, which is part of the index of this entry. Any non-zero bits would signify an entirely different entry.