You can test a field for alphanumerics or non-alphanumerics in character format. Various combinations of uppercase characters (A-Z), lowercase characters (a-z) and numeric characters (0-9) can be used.

For example, you can include only those records in which a 10-byte field contains only 'A'-'Z' characters (that is, uppercase characters) or '0'-'9' characters (that is, numeric characters). Or you can include only those records in which a 20-byte field contains characters other than 'a'-'z' (that is, lowercase characters).