An apparatus and method are provided for creating and revising programs for numerically controlled machines. First, generalized data block signals are produced, the generalized data block signals representing alphanumeric words defining block types, workpiece material types, work surfaces, workpiece features and machining operations. Then, machine control instruction block signals are produced in response to the generalized data block signals, the machine control instruction block signals represent alphanumeric words defining machine member motion in the form and format required by a particular numerical control. The generalized data program may be created by a machine operator using data obtained from the workpiece design data. Generalized data program creation and revision is accomplished without regard for the data requirements and limitations of a particular machine and control combination by which the workpiece is to be processed.