Billiard table all six pockets), with rounded entrances and nearly parallel sides, like those on a snooker table. One tactical consequence of this design difference is that the jaws of the WPA-type pocket are often used exactly like a horizontal version of the backboard of a basketball goal, to rebound the ball into the pocket; this technique does not work on blackball tables, and even shots down the cushion into a corner pocket are more difficult. For tournament competition under WPA world-standardized rules (and league play under derived rulesets), the bed of the pocket billiard table must be made of slate no
Billiard table the nap. , also known as (for their traditional shape), are inlaid at precise, evenly spaced positions along the rails of some tables (not usually on snooker tables) to aid in the aiming of bank or kick shots. There are seven along each long rail (with the side pocket interfering with where the seventh one would go, on pocket billiard tables) and three along each short rail, with each of the four corners counting as another in the mathematical systems that the diamonds are used to calculate. These sights divide the playing surface into equal squares. Books, even entire series