You can write audit entries that consist of only a string information string (and no memo data) by calling the Application_Auditor::Record() method. This method accepts as its first argument either a string or an instance of Application_Auditor_Message.

<?php
    // pass a string
    Application_Auditor::Record('Some action occurred');
    
    // pass an object
    Application_Auditor::Record(new Application_Auditor_Message('Some action occurred'));
?>