diff --git a/product/ERP5/Document/Category.py b/product/ERP5/Document/Category.py
index 1af46023d809b4778c0121e518c665e524168869..006f27480d9b8e758af1ee5465fed562e5a2d0ec 100755
--- a/product/ERP5/Document/Category.py
+++ b/product/ERP5/Document/Category.py
@@ -108,5 +108,7 @@ class Category(CMFCategory, Predicate, MetaNode, MetaResource):
     property_sheets = ( PropertySheet.Base
                       , PropertySheet.SimpleItem
                       , PropertySheet.CategoryCore
-                      , PropertySheet.Codification )
+                      , PropertySheet.Codification
+                      , PropertySheet.Reference
+                      , PropertySheet.SortIndex)