I do second Niels's proposal of ni for "not initial," as it would expand possibilities quite a bit. With the rest, of course, you're quite right.
Also, with parentheses notation, there should be some way to indicate "as many times as the board's size will allow," basically duplicating the function of a double atom letter. (If nothing else, it'd make copying those complex moves from one game to one with a larger board less of a hassle; no need to figure out manually what that number would be.) I've been using # in my own notes, but ! or " might make more sense.
Edit: Never mind the latter. It can be done by just using no number at all. At least, the PTA treats it that way.
I do second Niels's proposal of ni for "not initial," as it would expand possibilities quite a bit. With the rest, of course, you're quite right.
Also, with parentheses notation, there should be some way to indicate "as many times as the board's size will allow," basically duplicating the function of a double atom letter. (If nothing else, it'd make copying those complex moves from one game to one with a larger board less of a hassle; no need to figure out manually what that number would be.) I've been using # in my own notes, but ! or " might make more sense.
Edit: Never mind the latter. It can be done by just using no number at all. At least, the PTA treats it that way.