On the CAD-compatible conversion of S-patches

S-patches have many nice mathematical properties. It is known since their first appearance, that any regular S-patch can be exactly converted into a trimmed rational B'ezier surface. This is a big advantage compared to other multi-sided surface representations that have to be approximated for exporting them into CAD/CAM systems. The actual conversion process, however, remained at a theoretical level, with bits and pieces scattered in multiple publications. In this paper we review the entirety of the algorithm, and investigate it from a practical aspect.