9. A numerical control unit operative to machine a workpiece with a tool moving at a feedrate along a machining path under the control of a machining program comprising a plurality of blocks, at least one block defining a starting-point area and an end-point area along said machining path, said unit comprising: means for checking the position of said tool along said machining path; and means for changing a feedrate at each of the starting-point and end-point areas of a single block in the machining program, said means for changing being responsive to a command for changing the feedrate within the single block.
10. The numerical control unit as set forth in claim 9, wherein said feedrate is linear.