$username_letter = $conf->exists('username-letter');
$username_letterfirst = $conf->exists('username-letterfirst');
$username_noperiod = $conf->exists('username-noperiod');
$username_letter = $conf->exists('username-letter');
$username_letterfirst = $conf->exists('username-letterfirst');
$username_noperiod = $conf->exists('username-noperiod');