Is this dicussion about actual product surface quality, or about a methodology for surface design?
“Class-A” originally meant the perceptual quality of readily visible surfaces of a product, for example the exterior surfaces of a car. The surface quality is frequently assesed visually by the smoothness and flow of reflections, highlights and shadows but can also be assessed tactilely (by touch). Also contributing to the perceptual surface quality is the size and uniformaty of gaps and offsets/steps. Class-A surfaces predate the use of computers in design. In some instances achieving Class-A quality is highly dependent on the skill of the craftsman involved with making the tooling an/or object. Assessing Class-A quality can be context and observer dependent, similar to many if not all aesthetic assessments…
More recently “Class-A” has been used to describe methods of computational design which are based on use of single span Bezier patches or equivalent with suitable matching between patches. More complex surfaces are usually modeled by use of higher degree patches with more control points and increased number of control points. Not infrequently the statement is made that the use of multi-span patches is not allowed by “Class-A”. These methods are commonly used in the design of products which are intended to have “Class-A” surfaces. It should be noted that use of these methods does not guarantee the resulting surfaces will be “Class-A”, nor does the computational design of “Class-A” surfaces require the use of these methods.