Index: trunk/data/validator/addresses.mapcss
===================================================================
--- trunk/data/validator/addresses.mapcss	(revision 6927)
+++ trunk/data/validator/addresses.mapcss	(revision 6927)
@@ -0,0 +1,6 @@
+/* see #9667 - Verify interpolation range/values
+   Matches nodes with a decrease of addr:housenumber within addr:interpolation=even/odd.
+*/
+*[tag("addr:housenumber") > child_tag("addr:housenumber")][regexp_test("even|odd", parent_tag("addr:interpolation"))] + *[addr:housenumber] {
+  throwWarning: tr("Decreasing house numbers in addresses interpolation");
+}