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# NAME

CheckDigits::M10_008 - compute check digits for Sedol (GB)

# SYNOPSIS

``````  use Algorithm::CheckDigits;

\$sedol = CheckDigits('sedol');

if (\$sedol->is_valid('0123457')) {
# do something
}

\$cn = \$sedol->complete('012345');
# \$cn = '0123457'

\$cd = \$sedol->checkdigit('0123457');
# \$cd = '7'

\$bn = \$sedol->basenumber('0123457');
# \$bn = '012345'
``````

# DESCRIPTION

Prior to March 2004 SEDOL codes solely consisted of numbers. Since March 2004 SEDOL codes are a 7 character alphanumeric code.

The structure of the alphanumeric SEDOL codes is one alpha character followed by 5 alphanumeric characters followed by the numerical check digit.

Alpha characters are B-Z excluding vowels.
Alphanumerical characters are 0-9, B-Z excluding vowels.
Numerical Characters are 0-9.

No SEDOL code will be issued without the first alpha character. Active numerical SEDOL codes issued prior to March 2004 remain valid.

## ALGORITHM

0

All characters are assigned a numerical value from 0 to 35 where the characters '0' to '9' get 0 to 9, 'B' to 'Z' get 11 to 35 with the position of the vowels kept empty (for instance 'D' gets 13, 'F' gets 15).

1

Beginning left all numbers are weighted with 1,3,1,7,3,9 and 1 (checkdigit)

2

The sum of all products is computed.

3

The check digit is the difference of the sum from step 3 to the next multiple of 10.

## 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.

This function always returns the SEDOL code in upper case.

basenumber(\$number)

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

Return '' otherwise.

This function always returns the SEDOL base number in upper case.

checkdigit(\$number)

Returns the checkdigit of `\$number` if `\$number` has a valid check digit.

Return '' otherwise.

None by default.

# AUTHOR

Mathias Weidner, `<mamawe@cpan.org>`

# SEE ALSO

perl, CheckDigits, www.londonstockexchange.com Masterfile technical specifications V7.0.