This exploded view is of a post’s bottom stub tenon that is at the end of the sill.
The tenon is 2″ off the outside face, 2″ thick, and 2″ long. Due to the fact that it is at the end of the sill, it is trimmed back 2″ from the face of the post so that the mortise will have some “relish” to the end of the sill.