The message authentication code or hash/digest generated by the authentication process; when the Data Encryption Standard (DES) algorithm is used, the field consists of 4 hexadecimal coded characters (i.e., characters from the set 0..9, A..F), a separator character (space, "-", or other), and 4 hexadecimally coded characters; when non-DES hashes are used, the result of the hash is expressed as hexadecimally coded characters without spaces; when authentication or hash is not used, this field should be filled with a non-blank character other than the set (0..9, A..F) for the minimum length