The Sale Subscription Asset Tryton module adds the notion of asset to the sale subscription module.
The Sale Shipment Tolerance module adds under and over shipment tolerance on the sale. If the quantity of a sale line is under shipped but inside the tolerance percentage, then the line will be considered as fully shipped and no back-order will be created. If the quantity of a sale line is over shipped more than the tolerance percentage, then a warning is raised.
The Sale Supply Drop Shipment Tryton module adds a drop shipment option on product supplier if "supply on request" is checked. When checked, the purchase request and the linked purchase have the address of customer as Delivery Address; at the confirmation of the purchase a drop shipment is created and linked to both the purchase and the sale.