- debugXML.c hash.c tree.h valid.c : some changes related to
  the validation suport to improve speed with DocBook
- result/VC/OneID2 result/VC/OneID3 : this slightly changes
  the way validation errors get reported
Daniel
diff --git a/tree.h b/tree.h
index 47e0212..ce86711 100644
--- a/tree.h
+++ b/tree.h
@@ -172,6 +172,7 @@
 };
 
 typedef enum {
+    XML_ELEMENT_TYPE_UNDEFINED = 0,
     XML_ELEMENT_TYPE_EMPTY = 1,
     XML_ELEMENT_TYPE_ANY,
     XML_ELEMENT_TYPE_MIXED,