A digital Radio Frequency receiver may exhibit image frequencies and these image frequencies may be mathematically related to the intermediate frequency that is utilized for transmission and reception. The system uses two or more pre-stored spatially offset renderings of the pattern. The retainer includes an actuating portion that is externally engageable by the striker as the frames of the closure are slid closed to move the retainer to the non-retaining position. The optical element of the present invention may be used to tailor a conventional illumination system to the unique characteristics of the projection optics used in the photolithographic system, thereby compensating for vertical and horizontal bias or variations in line width for features oriented in the vertical and horizontal direction.