CATTRK
- based on a system of fixed marks: a straight
route (known as a recommended track, range or leading line), which comprises at least two
structures (usually beacons or daymarks) and/or natural features, which may carry lights
and/or top-marks. The structures/features are positioned so that when observed to be in
line, a vessel can follow a known bearing with safety. (adapted from International
Association of Lighthouse Authorities - IALA Aids to Navigation Guide, 1990)
- not based on a system of fixed marks: a route
(known as a recommended track or preferred route) which is not based on a series of
structures or features in line.