1. In topography, the crest of a sharply pointed ridge.
2. In ECDIS, a one-dimensional spatial object, located by two or more coordinate pairs (or two connected nodes) and optional interpolation parameters. If the parameters are missing, the interpolation is defaulted to straight line segments between the coordinate pairs. In the chain node, planar graph and full topology data structures, an edge must reference a connected node at both ends and must not reference any other nodes.