please refer to photo no:1 what is the extra "fastener/strap" in most DOmke bags for?? it has two hooks at the end. it comes hooked in the middle of the top protion of the bag?? is it to secure ..maybe a tripod or something?? and look at photo 2. there are two eyelets on the back portion of the bag. what are these for?? is it related to the strap i mentioned?? Thanks..