Yeah, you are right it is used more by white water rafters/kayakers. You also see them sometimes on backcountry packs. They are called lash tabs. You can see your design is similar to a clip you see on a knife sheath so it works well and puts the tab to great use. I carry a knife and rarely use it, also carry a camera and use it all the time when kayaking. I guess really the definition of Lash is to secure something down so it can be used for many purposed. I was taught that is where you put your knife and have seen many knifes with sheath clips designed specifically to clip to a lash tab.
http://www.austinkayak.com/products/...lot-Knife.html
I never thought about it until your post since I was narrow minded thinking it was just for knifes but a radio may clip in well to it also.