diff --git a/template/deep_process_schema.xsd b/template/deep_process_schema.xsd
index fa2d8db..8274443 100644
--- a/template/deep_process_schema.xsd
+++ b/template/deep_process_schema.xsd
@@ -40,7 +40,15 @@
             </xs:restriction>
         </xs:simpleType>
     </xs:element>
-    <xs:element name="command_line" type="xs:string" />
+    <xs:element name="command_line">
+        <xs:simpleType>
+            <xs:restriction base="xs:string">
+                <!-- the following minLength restriction takes the <![CDATA[ CMDLINE ]]> enclosure
+                 from the Process template file into account (= fails) -->
+                <xs:minLength value="15" />
+            </xs:restriction>
+        </xs:simpleType>
+    </xs:element>
     <xs:element name="loop" type="xs:string" default="no looping" />
     <xs:element name="comment" type="xs:string" default="no comment" />
   </xs:sequence>