Contradictory saslauthd

[Jeff Blaine <jblaine@xxxxxxxxxxxx>]

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."