Louis XIII writing table in walnut, turned baluster x-shaped legs.

Rectangular louis XIII writing table in walnut, turned baluster legs, x-shaped spacer and drawer on the front. Period: 17th century, tray certainly more recent. Origin: valais, switzerland. (uncertain) height: 71cm. Length: 85cm. Depth: 61cm. There is a small board attached to the rear panel that can be rotated and the use of which I don't know.