#23 - This is the link for APA rules.
http://www.poolplayers.com/tmanual.pdf
g. Causing even the slightest movement or altering the course of the cue
ball, even accidentally, is a foul. Even dropping the chalk on the cue ball
is a foul. It is not a foul, however, to accidentally move any other balls
(including the 8-ball) unless, during his turn at the table, a player moves a
ball and it in turn comes in contact with the cue ball. Any balls moved
accidentally during a shot must be replaced by the opponent after the
shot is over and all balls have stopped rolling. If it occurs before the shot,
it must be replaced before the shot is taken.
It's one thing not to have a rule book handy while your playing, but when people are sitting in front of a computer with all kind of search features, and they feel completely confident posting answers on a rules question without even trying to look up the rule themselves, you've gotta wonder sometimes.