Metre. Unit of length.

Distress Alerts, navigational warnings, meteorological warnings and forecasts and other important safety information for ships.

Modernised Australian Ship Tracking and Reporting System (replaces AUSREP).

Maritime Communications Station. Another term for a coast station.

A Mobile Earth Station in the Inmarsat system, which includes mobile, land, ship and airborne Inmarsat terminals. On a ship it is more commonly referred to as a Ship Earth Station (SES).

Meteorological Area: A meteorological service area with area limits similar to NAVAREA’s in the WWNWS.

Medium Frequency (300 to 3 000 kHz).

Medical and First Aid Guide. Part of the International Maritime Dangerous Goods Code.

Megahertz (1 000 000 hertz). A measurement unit of radio frequency, oscillation and vibration, equaling 1 000 000 cycles per second.

Maritime Identification Digit. A 3 digit decimal number used as the first part of ship station identity (MMSI) to indicate nationality.

Minimum Keyboard and Display. A minimal text only display provided for AIS Class–A transceivers.

Maritime Mobile Service Identity. The number used to identify coast stations’ and ships’ DSC, NBDP and AIS systems.

Mobile Packet Data Service. An Inmarsat service allowing continuous connection of ships to terrestrial networks with payment for volume of data exchanged, rather than the duration of ‘airtime’ used.

Maritime Rescue Coordination Centre. The Australian MRCC is located in Canberra and operated by AMSA (see also RCC and JRCC).

Marine Radio Operator’s Certificate of Proficiency. Replaced by Long Range Operator Certificate of proficiency.

Marine Radio Operator’s VHF Certificate of Proficiency. Replaced by Short Range Operator Certificate of Proficiency.

Maritime Safety Committee of the IMO.

Maritime Safety Information. Navigational and meteorological warnings, meteorological forecasts and other urgent safety related messages.

Maximum Usable Frequency. The highest frequency which is reflected by the ionosphere over any particular path.