--- a/lib/js/urweb.js	Wed Apr 30 13:05:54 2014 -0400
+++ b/lib/js/urweb.js	Fri May 02 15:32:10 2014 -0400
@@ -1942,6 +1942,19 @@
 }
 
 
+// Attribute name blessing
+
+function blessData(s) {
+    for (var i = 0; i < s.length; ++i) {
+        var c = s[i];
+        if (!isAlnum(c) && c != '-' && c != '_')
+            er("Disallowed character in data-* attribute name");
+    }
+
+    return s;
+}
+
+
 // CSS validation
 
 function atom(s) {