Stefano Lattarini [off-list ref] writes:
... But in that case, I'd like some assurance that such a character
is not going to be turned into a magical character some time in the
future ;-)
I'd say that any special letter could be considered a fair game by
the next person who would want a funky short-cut. If you used "S"
or something, e.g. "git branch S/ropic/1" etc., it would be very
unlikely to conflict with any such future changes.