Index: trunk/resources/data/validator/deprecated.mapcss
===================================================================
--- trunk/resources/data/validator/deprecated.mapcss	(revision 18524)
+++ trunk/resources/data/validator/deprecated.mapcss	(revision 18535)
@@ -2382,3 +2382,12 @@
 }
 
+/* #21836 */
+*[voltage-high],
+*[voltage-low] {
+  throwWarning: tr("{0} is deprecated", "{0.key}");
+  suggestAlternative: "voltage:primary";
+  suggestAlternative: "voltage:secondary";
+  group: tr("deprecated tagging");
+}
+
 /* When tags are deprecated they should be added to ignoretags.cfg too. */