Cavechat.org

Does anybody know what kind of rope was provided as foot slings on the old (pre-1972) Jumars? I identified it as probably linen in my book as the best guess of several cavers. I have recently purchased linen or flax rope on Etsy. (I now get spam at least once a week from Etsy.) Some on a climbers' forum identified the rope as sisal. I have seen sisal when it was sold as cheap twine and rope. I also have some sisal lariat rope. It is rougher than manilla, as is hemp. The Jumar rope is natural fibers, smoother and softer than manilla and not as soft as cotton.