diff --git a/data/rc.xsd b/data/rc.xsd
index 5893b41d..4887bb8e 100644
--- a/data/rc.xsd
+++ b/data/rc.xsd
@@ -348,6 +348,7 @@
     </xs:simpleType>
     <xs:simpleType name="button">
         <xs:restriction base="xs:string">
+            <!-- FIXME what??? -->
             <xs:enumeration value="Left"/>
             <xs:enumeration value="Middle"/>
             <xs:enumeration value="Right"/>