diff --git a/view/purchase_line_tree.xml b/view/purchase_line_tree.xml
index 3a8ebcca8b..2c4704a5ac 100644
--- a/view/purchase_line_tree.xml
+++ b/view/purchase_line_tree.xml
@@ -3,12 +3,12 @@
 this repository contains the full copyright notices and license terms. -->
 <tree>
     <field name="purchase" expand="1"/>
-    <field name="type"/>
-    <field name="product" expand="1"/>
-    <field name="product_supplier" expand="1"/>
-    <field name="summary" expand="1"/>
+    <field name="type" optional="1"/>
+    <field name="product" expand="1" optional="0"/>
+    <field name="product_supplier" expand="1" optional="1"/>
+    <field name="summary" expand="1" optional="1"/>
     <field name="quantity" symbol="unit"/>
     <field name="unit_price"/>
-    <field name="taxes"/>
+    <field name="taxes" optional="0"/>
     <field name="amount"/>
 </tree>
diff --git a/view/purchase_line_tree_sequence.xml b/view/purchase_line_tree_sequence.xml
index 251f13ba96..4be45f4e54 100644
--- a/view/purchase_line_tree_sequence.xml
+++ b/view/purchase_line_tree_sequence.xml
@@ -3,12 +3,12 @@
 this repository contains the full copyright notices and license terms. -->
 <tree sequence="sequence">
     <field name="purchase" expand="1"/>
-    <field name="type"/>
-    <field name="product" expand="1"/>
-    <field name="product_supplier" expand="1"/>
-    <field name="summary" expand="1"/>
+    <field name="type" optional="1"/>
+    <field name="product" expand="1" optional="0"/>
+    <field name="product_supplier" expand="1" optional="1"/>
+    <field name="summary" expand="1" optional="1"/>
     <field name="quantity" symbol="unit"/>
     <field name="unit_price"/>
-    <field name="taxes"/>
+    <field name="taxes" optional="0"/>
     <field name="amount"/>
 </tree>
diff --git a/view/purchase_tree.xml b/view/purchase_tree.xml
index 399545bc27..5528c776ad 100644
--- a/view/purchase_tree.xml
+++ b/view/purchase_tree.xml
@@ -2,14 +2,15 @@
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
 <tree>
+    <field name="company" expand="1" optional="1"/>
     <field name="number" expand="1"/>
-    <field name="reference" expand="1"/>
-    <field name="purchase_date"/>
+    <field name="reference" expand="1" optional="0"/>
+    <field name="purchase_date" optional="0"/>
     <field name="party" expand="2"/>
-    <field name="warehouse"/>
-    <field name="untaxed_amount"/>
+    <field name="warehouse" optional="1"/>
+    <field name="untaxed_amount" optional="0"/>
+    <field name="description" expand="1" optional="1"/>
     <field name="state"/>
     <field name="invoice_state"/>
     <field name="shipment_state"/>
-    <field name="description" expand="1"/>
 </tree>
diff --git a/view/template_tree.xml b/view/template_tree.xml
index c4fd34da41..7e007fa3a4 100644
--- a/view/template_tree.xml
+++ b/view/template_tree.xml
@@ -2,7 +2,7 @@
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
 <data>
-    <xpath expr="/tree/field[@name='default_uom']" position="after">
-        <field name="purchasable"/>
+    <xpath expr="/tree/field[@name='type']" position="after">
+        <field name="purchasable" optional="1"/>
     </xpath>
 </data>