Whoopie ridgelines -- often called adjustable ridgelines -- are what you indicate... cord spliced and configured to result in a fixed loop on one end and an adjustable on the other. pgibson nailed it; paracord is made of nylon. Nylon stretches -- a lot --- making it unacceptable for a ridgeline.
The photo above is great. This is a tutorial on attaching a ridgeline: