ISO/IEC 15045-2:2012(E) specifies a gateway architecture that provides an interconnection between one or more Wide Area Networks (WANs) and one or more Home Area Networks (HANs). It is not needed for a "simple gateway" linking one WAN to one HAN where there is no intention of future expansion. It applies to a "distributed gateway," and is also referred to in ISO/IEC 15045-1 as the Complex Modular Gateway. Also, it specifies how separate gateways in a single house can interoperate to provide co-ordinated functions.