For Retina cameras, you must say which specific normal lens is on your particular camera. There are two versions of long and wide angle supplementary lenses, depending upon which lens they are fitted to.
Yes, you are correct. I have the Schneider version and am thus looking of the Schneider lenses. i believe this is specific in my mentioning of the Longar and Xenon which are Specific to the Schneider’s and not the Rodenstock lenses.