 Consequently, a typical PCB will have multiple fiducials to allow placement robots to precisely determine the board's orientation.By measuring the location of the fiducials relative to the board plan stored in the machine's memory, the machine can reliably compute the degree to which parts must be moved relative to the plan, called "offset", to ensure accurate placement.Using three fiducials enables the machine to determine PCB offset in both the X and Y axes, as well as to determine if the board has rotated during clamping, allowing the machine to rotate parts to be placed to match.