The geometry of each edge or curve in Creo Parametric is described as a set of three parametric equations that represent the values of X, Y, and Z as functions of the independent parameter, t. For a surface, the three equations are functions of the two independent parameters u and v.

The Creo TOOLKIT functions described in this section provide the ability to evaluate the parametric edge and surface functions—that is, find the values and derivatives of X, Y and Z for the specified values of t, or u and v. They also provide for reverse evaluation.