alteration of the pitching motion

[_Bruno_]

guys,
Rule 8.01(a) The Windup Position. The pitcher shall stand facing the batter, his entire pivot foot on, or in front of and touching and not off the end of the pitcher's plate, and the other foot free. From this position any natural movement associated with his delivery of the ball to the batter commits him to the pitch without interruption or alteration.

what would you call an alteration during the pitching motion ? comming to a complete stop during the delivery (with no runners) ?

regards