This post is intended to answer my own question of a few weeks ago. I asked if a Schneider Super-Angulon XL 5.6 90mm would, because of its huge rear element, fi t on a Technikardan. Bob Solomon said it would not.
It fits fine. The only catch is there is a ring, (the Linsenchutzring, or lens g uard ring) on the rear element over which the rear cap fits. To fit through the hole on the front standard of the Technikardan this ring needs to be screwed off . So I leave the rear cap in place on this ring and screw off the ring and cap t ogether. The net difference is that I need to screw off the rear cap rather than pull it off. A small price to pay for an very large image circle (259mm) on a 9 0mm lens. If I ever see a concave rear cap that won't touch the rear glass then even that step would be eliminated.