All were soldered that I know of and on earlier Parkers a screw was used as well as the solder. The top of the screw head was filed to the same concave contour as the rib and either engraved with a flower blossom or, later when the rib was matted, the matting went right on over the screw head making it virtually invisible.
On barrels that have been refinished it is a lot easier to see the screw in the top of the rib extension.