Index: /trunk/data/validator/addresses.mapcss
===================================================================
--- /trunk/data/validator/addresses.mapcss	(revision 15143)
+++ /trunk/data/validator/addresses.mapcss	(revision 15144)
@@ -27,5 +27,8 @@
 
 /* #17486 */
-*[addr:housenumber][addr:housenumber!~/[0-9]/] {
+*[addr:housenumber=bb][inside("BA")] {
+  set ok_housenumber;
+}
+*[addr:housenumber][addr:housenumber!~/[0-9]/]!.ok_housenumber {
   throwWarning: tr("{0} without number", "{0.key}");
   assertNoMatch: "way addr:housenumber=0";