A sensing device for sensing a position relative to a surface. The surface has printed therein or thereon coded data including at least one data portion, and visible information, at least some of the coded data being coincident with the visible information. The sensing device includes a sensor for sensing at least one data portion when placed in an operative position relative to the at least one region and generating indicating data using the sensed data portion. The indicating data is indicative of a position of the data portion relative to the surface and an orientation of the sensing device relative to the data portion. The indicating data is then communicated to a computer system to allow the position of the sensing device relative to the surface to be determined.