The old sytle notation was designed to overcome the use of subscripts and double-decker number. The main inspiration for this is the Coxeter's Curtail. In essence, it creates the Gosset figures as pseudoregular, as far as the Schlaefli Symbol.
The way this is done is to pretend that something like the 221 is really a regular figure made up of faces {3,3,3,3}, and is thus something like a {3,3,3,3,B}. Something that has this as a vertex figure is {3,3,3,3,3,B}, or 321. There are three letters used in this manner, A, B and C. These represent the single stub branch of 1 in k11, k21 and k31.
The second variation was the use of slashes to denote where the curtail bends. Since something like 221 is written as 5B, the assorted rectified forms are shown with a single slash, eg /5B.
The next step was to develop the mirror-edge constrictions. In the end, I was working on mirror-margin constructions, but converted to the mirror- edge figures as an aside. So I accomidate mirror-margins with a backslash, eg \5B
It extends rather naturally: Q for "4", F for 5, H for 6, V for 5/2, T for 6/2 and so forth. A special branch E was introduced for a stub branch at the beginning of the chain, so the group {E,3,3,3,A} might be described.
Copyright 2002 Wendy Krieger