| term | meaning (click term for explanation in text) |
| cardinal mark | family of marks in the IALA buoyage system |
| chart datum | survey datum to which charted positions (latitude, longitude) are referred (same term is used for height datum to which depth are referred) |
| chart plotter | device which displays charts on a screen |
| chart 5011 | Admiralty publication: Symbols and Abbreviations Used on Admiralty Charts |
| daymark | an unlit structure built (and charted) to assist daytime navigation |
| direction light | a light which show in a particular direction |
| east cardinal | an IALA buoyage system mark in the cardinal mark family |
| fixed | a light showing on continuously |
| general direction of buoyage | the direction in which channels are defined by keeping port-hand marks to port and starboard-hand marks to starboard |
| height datum | datum to which charted heights above sea level are referred (usually MHWS) |
| IALA buoyage system | an internationally agreed convention for navigation marks, defining what they look like and how they are used |
| interrupted | a flashing light which stops flashing for a time them resumes |
| isolated danger mark | a mark in the IALA buoyage system showing an isolated danger |
| isophase | a light which shows alternately on and off for equal times |
| large scale | chart which shows a small geographical area in great detail |
| lateral mark | family of marks in the IALA buoyage system |
| light characteristics | the pattern and colour of a light, as described on a chart |
| luminous range | the brightness of a light, expressed as its nominal visible range in good visibility |
| mercator | a projection (q.v.) which is commonly used for marine charts |
| navigation | (see pilotage) set of techniques of getting from A to B, off-shore and not close to dangers |
| navigational aids | marks, lights and buoys placed to assist in navigation and pilotage |
| north cardinal | an IALA buoyage system mark in the cardinal mark family |
| occulting | a light which shows mainly on and goes off for short periods (the on periods are longer than the off periods) |
| period | the length of time it takes for a light pattern to repeat itself |
| pilotage | (see navigation) set of techniques for getting into or out of harbour and navigating close to dangers |
| port-hand lateral mark | an IALA buoyage system mark in the lateral mark family |
| preferred channel mark | an IALA buoyage system mark in the lateral mark family |
| projection | the technique used for representing the curved surface of the earth on a flat paper chart |
| region A | geographical area where IALA lateral marks are defined in a particular way (different from Region B) |
| region B | geographical area where IALA lateral marks are defined in a particular way (different from Region A) |
| safe water mark | a mark in the IALA buoyage system showing safe water or the entrance to a channel |
| scale | ratio between distance represented and distance on the chart |
| sectored light | a light which shows different colours in different directions |
| small scale | a chart which shows a large area with little detail of ports etc |
| south cardinal | an IALA buoyage system mark in the cardinal mark family |
| special mark | a mark defined in the IALA buoyage system which is placed for another purpose and is not a navigational aid |
| starboard-hand lateral mark | an IALA buoyage system mark in the lateral mark family |
| transit marks | marks which are arranged to line up guide vessels, e.g. into and out of a harbour |
| transverse mercator | a projection (q.v.) which is commonly used for marine charts |
| west cardinal mark | an IALA buoyage system mark in the cardinal mark family |
| WGS 84 | World Geodetic System 1984 - a chart surveying datum which is becoming standard because of ite compatibility with GPS |