Window mortise and tenon

Gary asked how the mortise and tenon in these windows works. It wasn't quite clear from my description. So, here is a picture where you can see how the tenon from the rails inserts into the mortise of the style.

But it is still not quite clear where the angled part of the style is, so I made a quick sketch, a crosscut through the mortise and the tenon.

Hopefully it is clear now?