+=item check_options HASHREF
+
+This method is called by 'insert' and 'replace' to check the options that were supplied.
+
+Return error-message, or false.
+
+(In this class, this is a do-nothing routine that always returns false. Override as necessary. No need to call superclass.)
+
+=cut
+
+sub check_options {
+ my ($self, $options) = @_;
+ '';
+}
+