SURFACE PAIR OFFSET BY NORMAL DISTANCE
Definition
An object is a <SURFACE PAIR OFFSET BY NORMAL DISTANCE> if and only if: it is an <ORDERED SURFACE PAIR>; the first item in the pair is an <ORIENTED SURFACE>, which is the basis; the basis surface has a well-defined normal direction at each point; the second offset surface is at a constant distance from the basis surface in the direction of the positive normal to the basis surface. as defined in ISO 15926 Part 3 Section 4.6.6.5