1978 carpet attachment along the B pillar

Does anyone know how the carpet attaches to the lip on the strike side pillar?  Runs along side the seat belts.  Previous owner put in new carpet but it flaps open along that edge on both sides.  The body edge is quite unfinished looking.  There is a "welt" sewed into the carpet before the end of the carpet. Is the carpet suppose to overlap the lip? I could not find anything in the AIM specific.  Thanks for your help.

Can you post picture(s) of the area? I think there should be a trim piece there....

The image is sideways, sorry don't know why it rotated.  The one pic is the top of the striker side door opening and the other is the bottom as you can see the rain diverter.  I did not find a trim piece mentioned in any carpet installation descriptions or videos.

Thanks for your help.

My '75 is not carpeted there -- it has hard plastic panels that wrap around that edge.  Is it possible that the carpet was added, and not a factory option?

On my "78, there is a rounded, hard plastic piece bonded to the inside of the carpet, that wraps over the flange or lip.  it's illustrated (unclearly) in the BODY section of the AIM.  A01-A12, page 22

Thank you baldwinpj, that makes sense. I don't have that attached to either side of the car/carpet.  I guess that's why previous owner left it flapping in the breeze.  The carpet is new-ish, not dirty or worn. I'll have to see if I can find out which vendor he purchased the carpet from and do some investigating with them.

Thanks again

So, yours has a molded, plastic/nylon channel bonded to the carpet there, and it just kinda "snaps" into place, and then a short trim piece at the bottom? Nice! Thanks for sharing the pic....I thought it was folded over like that, but I also thought there was a piece of trim the went farther up to hold it on. Now we know! 😎