Deprecated. Don't use for new development and try to migrate existing uses.
This function answers the question whether a given string representing an integer is modulus 10 check compliant (ie. whether the last digit of its modulus 10 checksum i zero).
This is thus the check to use as part of validating the integrity of any modulus 10 encoded integer string such as a social security number or an OCR-number.
If the string to check is either null or if it contains any character that is not a digit then the function will return a value of null.
Returns 1 if string is modulus 10 check compliant and 0 otherwise.