A workpiece is milled by a tool of a milling machine to form a desired
freeform surface. For this purpose, the tool is moved relative to the
workpiece along at least one tool path defined via support points. The
support points of the or each tool path are defined either in workpiece
coordinates or in machine coordinates. For each tool path, at least one
spline is produced in connection with the support points. The or each
spline is output to a control arrangement of the milling machine, which
controls the motion of the tool along the or each tool path on the basis
of the or each corresponding spline.