Your right about the basis for the formulation of the "A" "B" and "C" classes of cats Mary, But people forget that when they (the defineing dimensions) were originally set down, ALL those "classes" were defined within their appropriate "box rules", which was composed of only the barest minimun dimensions that would create separation from each other and try to stop various "in-between" sizes of cats from "muddying the waters" very much in the same way that the F18, F16, and F14's are defined today (but more simple). It has only been later as the relative classes became more formallised that more and more ridgid rule perimeters have been applied. and when the Tornado was "chosen" by the IYRU as THEIR Olympic class representative, it virtually stopped any further development of the "B" class of cats.
With the wind up of the IYRU and the passing of "ownership" of the control and "policing" of "International" classes to the ISAF, the ISAF have assumed that they are, literally the ultimate "owners" of the class rules of any class that becomes affiliated with the ISAF, and that they and only they have the final say as to the validity of any of the class rules of classes that allow themselves to come under the control of the ISAF (they - the classes - also have to pay the ISAF a very hefty "fee" for the privelige of being granted the title of "international" by the ISAF). So it is reasonable to say that all of those classes, the "A", "B", and "C", classes of cats all started life as "development" classes.
It was a little like the 18' skiffs in Australia that for many many years only had two rules, they had to be 18' long and the racing started at 2.30pm!, worked wonders for them for over fifty years!