All doors, windows, shutters of any sort in the 18th century had thru mortise and tenons, which means that the tenon runs completely through the stile for two reasons: First, for strength, second, for flatness. This is imperative - all parts must be FLAT and SQUARE !!! I use winding sticks on all my stiles and rails to ensure that they are even and level end to end. I mark my mortises and tenons off the face surface. This is most important on the stiles, which are marked on both edges. This ensures flatness. There cannot be any twisting of the frame !! There is no glueing to any of the parts here or of any of the above mentioned in the 18th century, thus pins, split(riven) as shown. They are made 2" long and tapered for an extremely tight fit. You'll see a pattern to the pinning if you look closely.