1. A computer numerical control system including coordinated machine control logic means and numerical control means for controlling the operation of a machine tool in the performance of a specified operation with respect to a workpiece, comprising: a bus connected central processing unit and a memory having a plurality of programs stored therein, said programs including, (a) a series of routines for implementing said numerical control means and being operable to control plural axis motions of said machine tool and being defined as the numerical control, (b) a series of routines for implementing said machine control logic means and being operable to control the auxiliary functions of said machine tool and being defined as the machine control logic, and (c) a series of routines and status flags for implementing a customization window interface between said machine control logic and said numerical control, said series of routines being accessible for execution by the central processor in response to execution of the machine control logic and said status flags being provided by the numerical control in response to the execution of said routines whereby the machine control logic controls the numerical control through the customization window under predetermined conditions so that coordination is attained therebetween.