I think notation would be intuitively more clear with punctuation characters rather than digits as suffix to lower-case letters. E.g. c' or c". That gives me an idea: the range-toggle could be decoupled from the move mode, by using a' for starting a new leg with range toggle, and plain a for starting a new leg of teh same type. That way the y and g on non-final legs could be deprecated.
I think notation would be intuitively more clear with punctuation characters rather than digits as suffix to lower-case letters. E.g. c' or c". That gives me an idea: the range-toggle could be decoupled from the move mode, by using a' for starting a new leg with range toggle, and plain a for starting a new leg of teh same type. That way the y and g on non-final legs could be deprecated.