On a sales order, when a product is selected, the product's description is automatically added (which can incidentally be updated without impacting the original product).

Our customers would like to see that the engineering drawing reference matches their purchase order, so we'd like to include this in each line.

We've added a custom field using Odoo's studio (file attachment).  I was hoping to add this field as a read-only field in the order line list using the Odoo studio, but I haven't been able to find the field (or any other product field for that matter) in order to add it. 

Am I missing something?

Update: 

I've got the file displaying as a download button. How do I change this to show the filename?