My understanding is that Rotation and 15 Ball are two different games. 15 Ball is played like 9 or 10 Ball (not sure if it's call shot or not though) with the last ball (15) being the money ball.
Rotation is a point based game with each ball being worth it's numerical value. The total value of the balls is 120 points and the player that scores 61 points is the winner. It is this game that I thought was big in the PI's.
Could be in some places, I really don't know. Here in Manila, Rotation & 15-ball are one in the same - the point based game.