generic design program in other words any variants generated for the purposes of display result from a point model of the object and some knowledge of how such points are connected mainly by straight lines arcs etc continuing with the example construction plan generator 34 would create a generic design program for the triangle as follows p 3 x 3 y 3 x 2 l 2 cos u03b1 2 y 2 l 2 sin u03b1 2 from the above it may not be readily apparent how the generic design program is utilized in relation to the replication design commands in order to generate a variable replication command in short such variable replication commands are achieved in the present invention by matrix mapping the variable design commands for example a longitudinal replication command i e copy horizontal or copy vertical may be represented by the following equation equ1 it is evident that the above matrix equation corresponds to x 2 y 2 l x 1 u03b4x y 1 u03b4y l as a result of such matrix mapping construction plan generator 34 need simply generate and store the quadratic matrix when including a variable replication command in a generic design program variants processor 35 in generating a variant substitutes parameter values for u03b4x and u03b4y in relation to the rotate replication command the following matrix map may be utilized equ2 such a matrix equation corresponds to x 2 x 1 cos u03b1 y 1 sin u03b1 and y 2 x 1 sin u03b1 y 1 cos u03b1 in this fashion construction plan generator 34 stores variable replication commands from the generic design program variants are generated through variants processor 35 in relation to specific parameter values variants processor 35 in the preferred embodiment consists of cad routines.