-A second parameter allows overriding of the syspref value. This is for testing only
-In usage use the DateTime objects own methods for non standard formatting
+This routine can either be passed a DateTime object or or a hashref. If it is
+passed a hashref, the expected keys are a mandatory 'dt' for the DateTime,
+an optional 'dateformat' to override the dateformat system preference, an
+optional 'timeformat' to override the TimeFormat system preference value,
+and an optional 'dateonly' to specify that only the formatted date string
+should be returned without the time.