Sorry, I had a "duh" moment when I posted the question. Somehow I got to thinking about a lining further down. (Kind of like a lady's slip, but sown into the kilt, for lighter fabrics.)

I have a copy of "The Book", and have been studying it. I understand w2f's explanation. Again, I had a "duh" moment and my mind went somewhere else. (Maybe I'll find it someday.) Thanks again for the info and sorry for the hijack.