Index: servers/rest_server/includes/rest_server.views.inc
===================================================================
--- servers/rest_server/includes/rest_server.views.inc
+++ servers/rest_server/includes/rest_server.views.inc
@@ -79,7 +79,7 @@
         }
         else {
           $assoc = TRUE;
-          $key = preg_replace('/[^a-z0-9_]/', '_', $key);
+          $key = preg_replace('/[^A-Za-z0-9_]/', '_', $key);
           $key = preg_replace('/^([0-9]+)/', '_$1', $key);
         }
         $element = $doc->createElement($key);