The present invention relates to a driving system for an automatic sliding door. The driving system includes a driver and a rack and pinion mechanism. The pinion is adapted to cause sliding movement of the door in a first or second direction when operatively connected to a corresponding rack associated with the door. The pinion is selectively attachable to the driver in two positions: (a) a first position in order to cause sliding movement of the door in the first direction; and (b) a second position in order to cause sliding movement of the door in the second direction. The present invention also relates to a device for indicating whether a driving system is suitable for driving a sliding door. The device includes a first end, a region including one or more calibrations; and a second end. The first end is adapted to be pulled by a user. The second end is adapted to be selectively and detachably attached to one of the calibrations. The region is located between the first end and the second end.