Add support for index values on xml output. Otherwise you will lose information about numeric array keys.

services-add_item_id_attribute-1653592.patch

diff --git a/servers/rest_server/includes/ServicesFormatter.inc b/servers/rest_server/includes/ServicesFormatter.inc
index 9799b19..8ce275a 100644
--- a/servers/rest_server/includes/ServicesFormatter.inc
+++ b/servers/rest_server/includes/ServicesFormatter.inc
@@ -61,6 +61,7 @@ class ServicesXMLFormatter implements ServicesFormatterInterface {
       $assoc = FALSE || empty($data);
       foreach ($data as $key => $value) {
         if (is_numeric($key)) {
+          $id = $key;
           $key = 'item';
         }
         else {
@@ -69,6 +70,9 @@ class ServicesXMLFormatter implements ServicesFormatterInterface {
           $key = preg_replace('/^([0-9]+)/', '_$1', $key);
         }
         $element = $doc->createElement($key);
+        if (isset($id)) {
+          $element->setAttribute('id', $id);
+        }
         $parent->appendChild($element);
         $this->xml_recursive($doc, $element, $value);
       }