@patrix - it was really that this question -
apple.stackexchange.com/questions/178309/… - prompted me to add mine. It was perhaps more to 'see it in print' on SE than because I couldn't have found it on Google;) Having said that, I hadn't looked up the Wikipedia page, ty for the link. Interestingly, it says the first Mac System I ever used, 6.0.6 on an SE30 was never actually released...