diff --git a/trytond/ir/ui/form.rnc b/trytond/ir/ui/form.rnc
index 83c2eec717..ecda2bd06b 100644
--- a/trytond/ir/ui/form.rnc
+++ b/trytond/ir/ui/form.rnc
@@ -206,6 +206,7 @@ attlist.group &= [ a:defaultValue = "1" ] attribute fill { "0" | "1" }?
 attlist.group &= [ a:defaultValue = "1" ] attribute rowspan { text }?
 attlist.group &= [ a:defaultValue = "4" ] attribute col { text }?
 attlist.group &= ( attribute name { text } | attribute id { text } )
+attlist.group &= attribute states { text }?
 
 hpaned = element hpaned { attlist.paned, child* }
 
diff --git a/trytond/ir/ui/form.rng b/trytond/ir/ui/form.rng
index 91133a840d..ba1c5c2905 100644
--- a/trytond/ir/ui/form.rng
+++ b/trytond/ir/ui/form.rng
@@ -747,6 +747,11 @@
       <attribute name="id"/>
     </choice>
   </define>
+  <define name="attlist.group" combine="interleave">
+    <optional>
+      <attribute name="states"/>
+    </optional>
+  </define>
   <define name="hpaned">
     <element name="hpaned">
       <ref name="attlist.paned"/>