The ability to legally pocket object balls, relies on the ability to stroke the cue ball in a straight line from
     point A to point B.  Point B, being called the “Point of Contact”, is the position, which the cue ball makes
     contact with the object ball at the point of contact when both balls are touching and lined up on an
     imaginary line (or chalk line drawn on the table) that travels through the centre of the balls to the centre of
     the balls to centre of the pocket.