NAME

       CheckDigits::MXX_001 - compute check digits for PA (DE)

SYNOPSIS

         use Algorithm::CheckDigits;

         $pa = CheckDigits('pa_de');

         if ($pa->is_valid('2406055684D<<6810203<0705109<6')) {
               # do something
         }

         $cn = $pa->complete('240605568_D<<681020_<070510_<_');
         # $cn = '2406055684D<<6810203<0705109<6'

         $cd = $pa->checkdigit('2406055684D<<6810203<0705109<6');
         # $cd = '6'

         $bn = $pa->basenumber('2406055684D<<6810203<0705109<6');
         # $bn = '240605568_D<<681020_<070510_<_'

DESCRIPTION

   ALGORITHM
       1.  Beginning left all digits are weighted with 7,3,1,7,3,1,...

       2.  The sum of those products is computed.

       3.  The checksum is the last digit of the sum from step 2 (modulo 10).

       4.  Step 1 to 3 is performed for every part of the number and for all 3 parts including
           the particular checkdigit to compute the total checksum.

   METHODS
       is_valid($number)
           Returns true only if $number consists solely of numbers and the last digit is a valid
           check digit according to the algorithm given above.

           Returns false otherwise,

       complete($number)
           The check digit for $number is computed and concatenated to the end of $number.

           Returns the complete number with check digit or '' if $number does not consist solely
           of digits and spaces.

       basenumber($number)
           Returns the basenumber of $number if $number has a valid check digit.

           Return '' otherwise.

       checkdigit($number)
           Returns the checkdigit of $number if $number has a valid check digit.

           Return '' otherwise.

   EXPORT
       None by default.

AUTHOR

       Mathias Weidner, <mathias@weidner.in-bad-schmiedeberg.de>

THANKS

       Aaron W. West pointed me to a fault in the computing of the check digit.

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de,
       www.export911.com/e911/coding/upcChar.htm, www.adams1.com/pub/russadam/upccode.html,
       http://www.upcdatabase.com.