an identifier related to the manufacturer, rather than a country's MID: 970YYxxxx The digitals represented by the two Y characters are assigned by the International Association for Marine Electronics Companies and refer to the SART manufacturer, while the Xs are sequential digits assigned by the manufacturer identifying the SART. Federal US MMSIs In the United States (one of whose MIDs is 366), federal MMSIs are assigned by the National Telecommunications and Information Administration, and are normally (but not always) formed as 3669xxxxx. Non-federal MMSIs are assigned by the Federal Communications Commission normally as part of the ship station license application, and are formed as 366xxx000 for ships on international voyages and ships needing an Inmarsat mobile earth station, or 366xxxxx0 for all other ships. The United States Coast Guard group ship station call identity is 036699999, and group coast station call identity is 003669999. In the U.S., MMSIs are primarily used for digital selective calling and for assigning Inmarsat identities. Exhaustion of MMSIs Because all ships on international voyages, as well as all ships fitted with an Inmarsat B or M ship earth station, are assigned MMSIs of the format MIDxxx000, a serious problem has arisen internationally in assigning sufficient numbers of MIDs to all administrations that need them. For example, a country having 10,000 Inmarsat-equipped ships would require 10 MIDs just to accommodate those 10,000 ships. If 50,000 boaters decided to fit small Inmarsat M terminals, 50 additional MIDs would be required to accommodate them. The problem exists with Inmarsat-equipped ships because ITU-T recommendations require that Inmarsat ship earth stations be assigned the identity (MESIN) TMIDxxxYY, where T indicates the type of Inmarsat station, YY indicates the Inmarsat station extension (e.g."00" might indicate a telephone in the bridge, "01" might indicate a fax machine in the radio room, etc.), and MIDxxx indicates the ship station number, which relates to the assigned ship station identity MIDxxx000. The MMSI was meant to be an all-inclusive ship electronic identity, used in one form or another by every GMDSS or telecommunications instrument on the ship. Questions have been raised, however, whether the MMSI can in practice totally fulfill that role. ITU may eventually end the practice of relating Inmarsat MESIN identities with the ship MMSI identity. To help mitigate against MMSI number exhaustion, manufacturers are required to cripple DSC-capable radios so that an MMSI number can only be entered once, which means that