NAME

       CheckDigits::M10_001 - compute check digits for Bahncard (DE), IMEI, IMEISV, ISIN,
       Miles&More, Payback (DE), Personnummer (SE), Passport (BR), Credit Cards, SSN (US),
       Samordningsnummer (SE), VAT RN (ES), VAT RN (IT), VAT RN (SE), International Securities
       Identifikation Number (ISIN)

SYNOPSIS

         use Algorithm::CheckDigits;

         $visa = CheckDigits('visa');

         if ($visa->is_valid('4111 1111 1111 1111')) {
               # do something
         }

         $cn = $visa->complete('4111 1111 1111 111');
         # $cn = '4111 1111 1111 1111'

         $cd = $visa->checkdigit('4111 1111 1111 1111');
         # $cd = '7'

         $bn = $visa->basenumber('4111 1111 1111 1111');
         # $bn = '4111 1111 1111 111'

DESCRIPTION

   ALGORITHM
       1.  Beginning right all numbers are weighted alternatively 1 and 2 (that is the check
           digit is weighted 1).

       2.  The total of the digits of all products is computed.

       3.  The sum of step 3 ist taken modulo 10.

       4.  The check digit is the difference between 10 and the number from step 3.

       To validate the total of the digits of all numbers inclusive check digit taken modulo 10
       must be 0.

   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>

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de.

       For IMEI, IMEISV: ETSI Technical Specification TS 100 508 (v6.2.0)