An optical information-bearing debit card having servo tracks and calibration works on a recording medium for aligning a reading or writing light beam with a nearby value site area. The medium is an elongated strip of reflective information storage material adhered to a self-supporting card, like a credit card. The value site area may be decremented by the light beam changing the optical characteristics of the recording medium. The servo tracks are lengthwise, parallel to the long dimension of the strip of recording material while the calibration marks are non-continuous marks, aligned in a track parallel to the servo tracks. Tracks and calibration marks are disposed on the card so that the value area can be read bidirectionally starting from either end of the card.