HP 3000 Manuals HP 3000 Manuals
CHECK DIGIT
Used to test the check digit in a numeric or alphanumeric field (modulus
10 or 11).
Syntax
{11}
CDIGIT {10} ["message"]
Parameters
message Specifies a custom error message.
Discussion
Check digit verification is a special check on a numeric or alphanumeric
field in which the last (rightmost) character is a check digit.
Verification can be either modulus 10 or modulus 11. (You can use
REFSPEC, as described in Section 5, to add a check digit to an existing
field value in a batch file.)
Modulus checks are used when the risk of error keying in numbers must be
reduced to a minimum. Depending on the modulus selected, single digit
errors, and single or double transpositions can be checked using a check
digit. Modulus 10 detects single transpositions and incorrect keying of
a single digit. Modulus 11 detects these, plus double transpositions.
(Refer to Appendix D for an exact description of the modulus 10 and 11
checks.)
In general, a check digit is arrived at by performing calculations on a
number and then using the result of these calculations as the final digit
or "check digit" in that number. For example, suppose a 5-digit charge
account number is to be assigned to a new account. The specified
calculations (modulus 10 or 11) are performed on the 5-digit number, the
result is added as a check digit to the number, and a 6-digit number is
assigned as the new account number.
Thereafter, when this number is keyed in and the CDIGIT edit test is
selected, then the last digit is checked against the same calculations.
If the number was keyed incorrectly, an error is diagnosed.
Note that a number derived using modulus 10 calculations can only be
checked by CDIGIT 10, and a number derived using modulus 11 can only be
checked by CDIGIT 11.
Letters of the alphabet can be checked by either a modulus 10 or 11
check. Digits are assigned to the letters so they can be treated like
numbers. Thus a field with a check digit can contain a mix of numbers
and letters, but must not contain any special characters. Any initial
plus or minus sign is ignored.