A ball's "drilling layout" refers to how and where holes are drilled, in relation to the ball's locator pin and mass bias (MB) marker. Layout is determined with reference to each bowler's "positive axis point" (PAP; the pocket end of the ball's initial axis of rotation). "Pin down" layouts place the pin between the finger holes and the thumb hole, while "pin up" layouts place the pin further from thumb hole than the finger holes (see photos). Bowling ball motion is influenced by how far the pin and the mass bias (MB) are from the PAP, the distances determining "track flare." Track flare—the sequence of oil rings showing migration of the ball's axis on successive revolutions through the oil pattern—is popularly thought to influence entry angle, but Freeman & Hatfield (2018) discount its contribution to ball motion.