13. The printing system comprising: a print head; means for moving the print head along a printing path extending in a predetermined direction to effect printing along the printing path; means for positioning a receipt tape in a receipt tape zone extending transversely across the printing path so that the print head effects printing on the receipt tape; means for positioning an alternative document in an alternative document zone overlying the receipt tape zone and extending transversely across the printing path and laterally beyond at least one end of the receipt tape zone in the predetermined direction so that the print head effects printing on an alternative document instead of the receipt tape; first and second document detection means positioned on opposite sides of the printing path adjacent the receipt tape zone for detecting the presence of a document in the alternative document zone and for producing a predetermined output; and document advancing means for selectively advancing either the receipt tape through the the receipt tape zone or the alternative document through the alternative document zone depending on the output of the detection means.
13. The printing system comprising: a print head; means for moving the print head along a printing path extending in a predetermined direction to effect printing along the printing path; means for positioning a receipt tape in a receipt tape zone extending transversely across the printing path so that the print head effects printing on the receipt tape; means for positioning an alternative document in an alternative document zone overlying the receipt tape zone and extending transversely across the printing path and laterally beyond at least one end of the receipt tape zone in the predetermined direction so that the print head effects printing on an alternative document instead of the receipt tape; first and second document detection means positioned on opposite sides of the printing path adjacent the receipt tape zone for detecting the presence of a document in the alternative document zone and for producing a predetermined output; and document advancing means for selectively advancing either the receipt tape through the the receipt tape zone or the alternative document through the alternative document zone depending on the output of the detection means. 16. The printing system according to claim 13 wherein one of the document detection means comprises means for directing a light beam through the portion of the alternative document zone extending laterally beyond the receipt tape zone, and means responsive to the light beam for indicating the presence of a document in the alternative document zone.