GNU programs seem to use this format:

   $ ls --help | grep ',.*=[A-Z]'
     -I, --ignore=PATTERN       do not list implied entries matching shell PATTERN
     -T, --tabsize=COLS         assume tab stops at each COLS instead of 8
     -w, --width=COLS           set output width to COLS.  0 means no limit

The argparse format is more accurate, but also less practical, especially for long variable names.