The first two letters of the key form indicate the form that key type 1 parameter is in, and the second two letters indicate the form that key type 2 parameter is in.

 Key   Type Type   
 Form   1    2

 OPIM  DATA DATA  Use the OP form in encipher. Use key export with the
                  OP form to communicate ciphertext and key with
                  another cryptographic partner. Use key import at a
                  later time to use encipher or decipher with the same
                  key again.
 OPIM  MAC  MAC   Single-length MAC generation key. Use the OP form in
                  MAC generation. You have no corresponding MACVER key,
                  but you can call the MAC verification service with
                  the MAC key directly. Use the key import callable
                  service and then compute the MAC again using the MAC
                  verification callable service, which compares the MAC
                  it generates with the MAC supplied with the message
                  and issues a return code indicating whether they
                  compare.