I think that there are exactly eight types of strokes, I gave them two-letter codes:
Sweeping is trapped-to-trapped, and is US and DS (for “upward sweep” and “downward sweep,” respectively).
Single-escaped motions exiting are UX and DX, and entering (getting trapped) are DT and UT.
Doubly-escaped motions are going down and up, DD and UU.
So, those are all eight. To give you an example, if I do “2WPS” with 3 notes that might be DT, US, DX, although I am told that some people here might do DD, UT, DX, etc.
So complete systems of playing are “DWPS” (= DT + UX), “UWPS” (= UT + DX), “2WPS” = (DT + UX + UT + DX), “double-escaped” (= CC + DD).
So if I’m sweeping three strings I’ll go (say) DT, DS, DX.
This notation seems useful for discussing some of the CtC ideas. Of course the notation can be made more compact with just one letter, but that seems excessive.
For theorists: (a) trapped is defined as being below the string plane, (b) there are strokes that miss the strings entirely, I just put a parenthesis around what would have happened had I hit the string, and ( c) DT or UT might or might not be a rest stroke, this notation doesn’t say.
Finally, it is interesting to think of DT = -UX, etc., but that seemed too opaque.