NAME

CheckDigits::M11_011 - compute check digits for VAT Registration Number (NL)

SYNOPSIS

  use Algorithm::CheckDigits;

  $ustid = CheckDigits('ustid_nl');

  if ($ustid->is_valid('123456782')) {
        # do something
  }
  if ($ustid->is_valid('123456782B04')) {
        # do something
  }

  $cn = $ustid->complete('12345678');
  # $cn = '123456782'
  $cn = $ustid->complete('12345678.B04');
  # $cn = '123456782B04'

  $cd = $ustid->checkdigit('123456782');
  # $cd = '2'
  $cd = $ustid->checkdigit('123456782B04');
  # $cd = '2'

  $bn = $ustid->basenumber('123456782');
  # $bn = '12345678';
  $bn = $ustid->basenumber('123456782B04');
  # $bn = '12345678.B04';

DESCRIPTION

This VATRN has 12 "digits", the third last must be a B, the fourth last is the checkdigit. I don't know anything about the meaning of the last two digits.

You may use the whole VATRN or only the first eight digits to compute the checkdigit with this module.

ALGORITHM

Beginning right with the digit before the checkdigit all digits are weighted with their position. I.e. the digit before the checkdigit is multiplied with 2, the next with 3 and so on.
The weighted digits are added.
The sum from step 2 is taken modulo 11.
If the sum from step 3 is 10, the number is discarded.

Returns true only if the first eight positions of $number consist solely of digits (maybe followed by 'B' and to further digits) and the eighth 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 inserted at position eight of $number.

Returns the complete number with check digit or '' if $number does not consist solely of digits a dot and maybe 'B' at the ninth position.

basenumber($number)