
upc -- Print UPC-A (Universal Product Code) barcode of a number (to an
       Epson FX-80) : External command, version 1.0 / by Jeff Hansen

syntax:   upc <string> [-s <integer>] [-l <integer>] [-d]

ex:       upc 7567821672
          upc 7599263162 -l30
          upc 7599258014 -d
          upc 7674260082 -s3 -d

Prints a UPC (type A) barcode for a character string input.  Enter the
number with no spaces.  The code must have a length of 10 digits.  UPC uses
different ciphers for the left and right halves of the code (and has a
center, in addition to star and stop characters). The barcode is printed in
'double-strike' mode, so the printer's pins will overlap, producing a uniform
vertical bar.  The check digit is automatically calculated.

Valid barcode characters are: 0123456789

options:

          -s   UPC system digit (0-9).  Default is zero (0).  The system
               digit defines the type of product being coded (0 for general
               merchandise).

          -l   Left margin offset, from 0 to 60.  Default is six (6).

          -d   Print barcode double size.  For each vertical bar, 2 adjacent
               bars are sent to the printer.  Default is single size (1).

               Double sized barcodes are printed at 120 dpi, single at 90 dpi.
