ALGORITHM¶

1.

Beginning left all digits are weighted 2,3,4,5,6,7,1,6,7,2,3. Letters are replaced according to the following table:

  my %table_to = (
        A => 12, B => 14, C => 16, D => 18, E => 20,
        F => 22, G => 24, H => 26, I => 28, J => 6,
        K => 8, L => 10, M => 12, N => 14, O => 16,
        P => 18, Q => 20, R => 22, S => 4, T => 6,
        U => 8, V => 10, W => 12, X => 14, Y => 16,
        Z => 18,
  );
    

2.

The weighted digits are added.

3.

The sum from step 2 is taken modulo 11.

4.

The checksum is 11 minus the sum from step 3.

If the difference is 10, the checkdigit is 0.

If the difference is 11, the checkdigit is 1.

METHODS¶

is_valid($number)

Returns true only if $number consists solely of numbers, letters and hyphens and the rightmost 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 appended to the end of $number.

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

basenumber($number)

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

Return '' otherwise.

checkdigit($number)

Returns the check digits of $number if $number has valid check digits.

Return '' otherwise.

EXPORT¶

None by default.