Apache Reference: mod_auth_anon, Anonymous_NoUserId

Anonymous_NoUserId

Specify Whether User IDs Can Be Empty
Syntax: Anonymous_NoUserId on|off
Example: Anonymous_NoUserId on
Since: Apache 1.1

When this directive is set to ``on'', users can leave the user ID (and perhaps the password field) empty. This option can prove very convenient for users of GUI-based browsers, who can then simply hit the Return key or click directly on an OK button.