Each printout contains the serial number of the RBT IV printer and the serial number of the Alco-Sensor IV that was used for that test.  If you can, just press the LAST TEST button to view the serial numbers on the printed result.
  The Alco-Sensor IV serial number is on the back of the instrument, either in a box on the back label (top circle)
OR  underneath the bar code (bottom circle).
The serial number of the RBT IV is printed
underneath the paper cover.