<p>
Some Z39.50 servers require authentication before access is
allowed. For such servers, a suitable username and password may be
provided. Server that require authentication but for which no
username/password is provided cannot be tested.
</p>
<p>
At the time of writing there is no standard way to provide
authentication to SRU/SRW services, so these fields are of limited
utility for such services.
</p>