$session->insertElement_P($object,
    $relation,
    [ $type, $value ])

The InsertElement_P() function inserts something into a relationshipset.

In order to access the low-level primitive version of this call, you must invoke it by using the primitive method because the InCharge::session module also has its own variant.

 $session->insertElement_P(,"Router", "ComposedOf",
     [ "OBJREF", "Fan::fan1" ]);