A directed distance along a curved line is not a vector and is represented by a segment of that curved line defined by endpoints "A" and "B", with some specific information indicating the sense (or direction) of an ideal or real motion from one endpoint of the segment to the other (see figure). For instance, just labelling the two endpoints as "A" and "B" can indicate the sense, if the ordered sequence ("A", "B") is assumed, which implies that "A" is the starting point.