When the mobile device is used in order to receive purchase orders, (Purchase order line receiving of purchase order item receiving) we first have to scan or enter the purchase order number.
When a carrier arrives with the goods, the documents he has, usually do not have a barcode with the purchase order on it.
Entering the purchase order on a mobile device is not always an option. So the only option to be able to do a receipt is to print all of the expected arrivals and print the purchase order number (and also the item number) in barcode on the product receipt list in order to be able to scan the purchase order and the item number (as item number can't be scanned either in a lot of cases, for example when the item number is part of an EAN128 barcode on the LP, which is not supported by AX).
In order to have a paperless receipt it would be nice to have a drop down on all open purchase orders. If you would be able to first select the vendors with open orders, the list of open purchase orders could be limited.
If the purchase order was selected, it would also be nice to have an overview of all the open purchase order lines and be able to select the order line (item) to receive.

there are also other flows where drop downs could be useful. For example report as finish production orders, receiving RMA,...

In the current flows it is not possible to receive paperless.