This used to be fairly common on large tins. The tab was free to move around the rim of the lid. You would pull up on the tab, which would act as a lever to pry up that part of the lid. Then you could slide the tab part way around and repeat until the lid popped off. It worked great and you didn't have to scrounge around for something to open the can.It looks to have a weird opening mechanism on it. Kinda like a pull tab but not.