diff --git a/bin/addons/base/rng/view.rng b/bin/addons/base/rng/view.rng
index e40f178d69f..5496f8b16a2 100644
--- a/bin/addons/base/rng/view.rng
+++ b/bin/addons/base/rng/view.rng
@@ -156,6 +156,7 @@
         <rng:element name="notebook">
             <rng:optional><rng:attribute name="position"/></rng:optional>
             <rng:optional><rng:attribute name="colspan"/></rng:optional>
+            <rng:optional><rng:attribute name="tabpos"/></rng:optional>
             <rng:oneOrMore>
                 <rng:ref name="page"/>
             </rng:oneOrMore>