English

The ORIGIN of a system in the rectan­gular system of SURVEYS of which a PRINCIPAL MERIDIAN and a BASE LINE constitute the axes for a given area. Also called fundamental point.

An ICE SHEET of considerable thick­ness and more than about 50,000 sq. km in area, re­sting on ROCK. Inland ice sheets near SEA LEVEL may merge into ICE SHELVES.

The digital satellite communications system for store-and-forward text or data messaging using mobile terminals with omni-directional antennas. Inmarsat-C is the only system (2011) that allows ships to meet the majority of the satellite communication requirements of the GMDSS including distress alerting, reception of MARITIME SAFETY INFORMATION and general communications.

Navigation through certain sea areas of a coastal State without being prejudicial to the peace, good order or security of that State. See also TRANSIT PASSAGE.

Leading mark based on the interference effect of 3 separately placed rasterboards. An arrow pointing in the direction of the line is displayed when not sailing along the leading line.

What is put in, as electric current or other power put into a machine. DATA to be transferred from an external storage medi­um, such as punched cards, into the internal STORAGE of a COMPUTER.

In CARTOGRAPHY: a) a small area outside the NEAT LINES of a MAP or CHART included within the NEAT LINES or borders to avoid publishing a separate gra­phic of the small area alone; b) a representation of a small area on a larger SCALE (e.g., town-plan inset), or of a large area at a smaller SCALE (e.g., orientati­on inset); c) any information, not normally appearing within the geogra­phic limits of a MAP, which has been enclosed by border lines and included within the map neat lines. Insets are always placed in areas where important features will not be obs­cured.

A ROUTEING measure comprising a designated area between the landward boundary of a TRAFFIC SEPARATION SCHEME and the adjacent COAST, to be used in accordance with the provisions of rule 10(d), as amended, of the International Regulations for Preventing Collisions at Sea , 1972 (Collision Regulations).

Property of the state of rest or continu­ous movement of a system such that any disturbance intro­duced into this state grows. In METEOROLOGY, the term is often used as a synonym of STATIC INSTABILI­TY.

State of hydrostatic equilibrium of the ATMOSPHERE in which a particle of air moved from its initial level undergoes a hydrostatic force which tends to remove it further from this level. Also called hydrostatic instability.

Man-made structure usually built for the exploration or exploitation of marine resour­ces, marine scientific research, tide observations, etc.