

line - A basic geographic element, defined by an ordered set of
points, that describes the position and shape of a linear feature on 
a map.  In GRASS usage, the term line does not necessarily refer to
a straight line, but merely to a series of \arcs\ (vectors) forming
the perimeter of a linear feature (e.g., stream or railroad).  Arcs
that form linear features are sometimes called lines, and arcs that
outline \areas\ are called area edges or area lines.
