The Constant-Velocity motion-law is defined by its Velocity.
The Position at the end of a segment that is defined by a Constant-Velocity motion-law is a function of the Start-Position and the Segment-Width. However, it is often useful to enter the Start Position and End-Position, and the motion to be constant-velocity, also. You must use the Flexible-Polynomial to do this 'motion-law'.
Flexible-Polynomial : Two Position | Constant-Velocity
Constant-Velocity: 'Conveyor' Motion-Law