> who is stationed permanently onsite at the client Not really necessary. The distinction between FDEs and product engineers is that the FDE work is focused on

> who is stationed permanently onsite at the client Not really necessary. The distinction between FDEs and product engineers is that the FDE work is focused on a single deployment, whereas a product engineer works on a single product and is once-removed from actual clients. Where the FDE spends time and what products he works on depends on the client requirements.