Questionable ZIP Codes may be determined by the ZIP +4 software. Erroneous ZIP Codes
can occur if the U.S. Postal Service database information is incorrect or if the address
information keyed contains errors (i.e., South Dr instead of South St).
ZIP Code Alerts may be generated by Central Office (CO) to the Program Centers (PCs)
or field offices (FOs) when there are ZIP Code discrepancies.