Division 2.1.1

The major components of the S-52 presentation library are:

• a library of symbols, line styles and fill styles,

• a colour coding scheme which includes the IHO colour tables for day, dusk and night time,

• a set of symbology command words from which machine readable instructions can be assembled. The result is a symbology instruction, which is processed to symbolise ENC features in turn,

• a set of conditional symbology procedures to decide the appropriate symbolisation in cases determined by the mariner's selection (e.g. safety contour) or for complex symbols (e. g. top marks on buoys and beacons),

• a set of look-up tables that link feature descriptions from the ENC to the appropriate symbology instructions depending on whether:

• the link is straight forward, i.e. a direct relationship between a feature's description and its presentation such as a buoy or a land area. In this case, the look-up table provides the symbology instruction to show a symbol, an area fill, or a line style,

• the link is conditional, i.e. depending on circumstances, for example a depth area, whose colour fill depends on the choice of the safety contour. In this case the look-up table refers the decision to a conditional symbology procedure that selects the appropriate symbology instructions later.