I guess we shall never know the whole truth, but I am prepared to accept the history of I-MARC as I described it above, and VH-JCG as given. I think there were 2 parallel cn series for the different variants. As to I-MARK, I have not heard of it. I-MARK was an SF-260 from 1969. http://www.siai-marchetti.nl/sf260/2-35.html