I've just come into possession of a Dutch army hooped bivi bag. Pretty decent piece of kit all told. I have a question though. Does anyone know what the straps are for that are located on the back/underneath of the bag. There are one on each shoulder, one big one right across the middle and two at the feet. Bearing in mind that when in use these straps will be on the ground, I can't figure out what on gods green earth they are for. It's probably blindingly obvious and if so please feel free to take the complete piss out of me! I'm thinking they may be to hold a bed roll in place.