I seem to have found the answer to my own question.
All continuously variable shutter are in fact more correctly described as semi-continuously variable. Continuous variables are variables that must take a value between their minimum and maximum, and all cameras have maximum and minimum shutter speeds. It appears that later Contax and Yashica cameras alone used the correct terminology in their literature.
I could not see any difference, apart from displays showing steps which did not exist. Some showed the exact speed figure, most did not. The continuous scale of an auto shutter meant less parts, only a timing circuit to trip and stop the exposure, compared to a mechanical timer on a similar shutter.
Although the auto shutter gives an exact figure, it was never really required with the huge exposure latitude of film. The quartz timers were the next type, and came from the shutter makers using watch timer units, after all both Copal, Seiko, etc were watch makers, and the quartz circuits were more reliable than R/C circuits.
I am going to stick my neck out and possibly get my head chopped off. But I have been dormant for so long that I will take a chance.
Continuously variable - Speed adjustment may be stopped anywhere on the shutter speed scale. Even in between the indicated speeds. Thus, for example, stopping between 60 and 125 sec. will give any speeds between the two numbers such as 1/80th second. Particularly useful on long shutter speeds.
Semi continuous variable - Continuous on the slower part of the speed scale. But must be set at marked numbers for faster speeds where the space between speeds would not give very much variation.
Last Edit: Feb 18, 2016 5:19:52 GMT -5 by mickeyobe