All holes in a bowling ball must be used on every delivery.  Balance holes are not permitted.  Bowlers who do not use their thumb when delivering the ball will need to
mark, by scribe or engraver tool, a plus sign (+) near the intended
center of the palm.

Rule 18, which allows for the use of isopropyl alcohol to clean a ball
during competition and Rule 113a which allows for the use of a single
lane during competition has also been extended for the 2021-2022 season.