Index: trunk/data/validator/deprecated.mapcss
===================================================================
--- trunk/data/validator/deprecated.mapcss	(revision 7697)
+++ trunk/data/validator/deprecated.mapcss	(revision 7707)
@@ -340,2 +340,6 @@
   fixChangeKey: "place_name => name";
 }
+
+way[sidewalk=yes] {
+  throwWarning: tr("{0}={1} is unspecific. Please replace ''{1}'' by ''left'', ''right'' or ''both''.", "{0.key}", "{0.value}");
+}