The scale in Z direction element is a numeric variable defining an active object's magnification scale in the Z axis direction (forward - backward direction). After an object is created, the Z scale starting value = 1. By setting the element to a number greater than 1 the object will get magnified in the Z direction, by setting the element to a number smaller than 1 the object will get minified. The zero setting makes the object "flat". By entering a negative scale the object will get "inverted" (including the face orientation inversion). The change of scale is performed before rotation and translation transformations are intended to be done.