Dean,
This particular treatment is an exact copy of the side panels on many Francotte boxlock shotguns imported by Von Lengerke & Detmold prior to 1910. It was known as a "scalloped and checkered sidelock-shaped side panel". Here is a photo of an image from an original salesman's display card of the period which I have annotated for current owners requesting information or indentification of models.
Bob Beach
Griffin & Howe, Inc