Contradictory saslauthd

[Jeff Blaine]

I'm not being flippant here.  I want to understand what I am
doing (or failing to do).  This seems contradictory to me
below.  What am I not privvy to?

"DESCRIPTION
      saslauthd is a daemon process that handles  plaintext
      authentication requests on behalf of the SASL library.
...
    -a
...
      kerberos4  (All platforms)

                 Authenticate against the local Kerberos 4  realm.
                 (See the NOTES section  for  caveats  about   this
                 driver.)

      kerberos5  (All platforms)

                 Authenticate against the local Kerberos 5 realm."