New Snippet/Field

snippets/account.view_move_form.x_drawing_file.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<data inherit_id="account.view_move_form" priority="50">
+    <field name="product_id" position="after">
+        <field name="x_drawing_file" optional="hide"/>
+    </field>
+</data>

snippets/ir_model.account_move_line.x_drawing_file.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<odoo>
+    <record id="x_drawing_file" model="ir.model.fields">
+        <field name="field_description">Zeichnung</field>
+        <field name="model">account.move</field>
+        <field name="model_id" ref="account.model_account_move_line"/>
+        <field name="name">x_drawing_file</field>
+        <field name="store" eval="False"/>
+        <field name="readonly" eval="True"/>
+        <field name="copied" eval="False"/>
+        <field name="ttype">many2one</field>
+        <field name="related">product_id.drawing_file</field>        
+    </record>
+</odoo>