Index: /trunk/data/validator/ignoretags.cfg
===================================================================
--- /trunk/data/validator/ignoretags.cfg	(revision 15472)
+++ /trunk/data/validator/ignoretags.cfg	(revision 15473)
@@ -154,4 +154,5 @@
 ; Misc Tags
 ;
+K:traffic_calming=dynamic_bump
 K:type=is_in
 K:type=benchmark
Index: /trunk/data/validator/wikipedia.mapcss
===================================================================
--- /trunk/data/validator/wikipedia.mapcss	(revision 15472)
+++ /trunk/data/validator/wikipedia.mapcss	(revision 15473)
@@ -1,3 +1,3 @@
-/* validation for the wikipedia=* tag - see tickets #8383, #14425 */
+/* validation for the wikipedia=* tag - see tickets #8383, #14425, #18251 */
 
 /* If there is no language at all, this is broken. Also catches 'wikipedia' used as 'email', 'website', 'ele' [sic!] ... */
@@ -52,4 +52,12 @@
   assertMatch: "node wikipedia=en:Foo%27s";
   assertNoMatch: "node wikipedia=en:Foo";
+}
+
+*[/^wikipedia:[-a-z]{2,12}$/][/^wikipedia:[-a-z]{2,12}$/ =~ /(?i).*%[0-9A-F][0-9A-F]/] {
+  throwError: tr("{0} tag should not have URL-encoded values like ''%27''", "{0.key}");
+  /* fixAdd: concat("{0.key}", "=", get(regexp_match("(?i)^([-a-z]+:)(.*)$", tag("{0.key}")),1), trim(replace(URL_decode(get(regexp_match("(?i)^([-a-z]+:)(.+)$", tag("{0.key}")),2)), "_", " "))); */
+    /* tag("{0.key}") is not yet supported */
+  assertMatch: "node wikipedia:de=Foo%27s";
+  assertNoMatch: "node wikipedia:de=Foo";
 }
 
@@ -138,7 +146,7 @@
 }
 
-/* Wikipedia without wikidata */
+/* Wikipedia:lang without wikipedia */
 *[!wikipedia][/^wikipedia:/] {
-  throwWarning: tr("wikipedia tag is not set, but a ''{0}'' tag is. Make sure to use wikipedia=language:value together with wikidata tag.", "{1.key}");
+  throwWarning: tr("''{0}'' tag is set, but no ''{1}'' tag. Make sure to set ''wikipedia=language:value'' for the main article and optional ''wikipedia:language=value'' only for additional articles that are not just other language variants of the main article.", "{1.key}", "{0.key}");
   assertMatch: "node wikipedia:en=a";
   assertNoMatch: "node wikipedia=a wikipedia:en=b";