A hot dog is not a sandwich. A sandwich must by definition include
two entirely separate slices of bread. I will allow for a third slice, but four or more is just getting silly. Splitting open a bun such that it remains hinged falls outside the definition of a sandwich. A hot dog is a sub,
which I also do not consider to be a sandwich. Unless the twit behind the counter at Subway accidentally slices all the way through the bun, or the condiments and sauces make it so soggy that it splits on its own, as so often seems to happen to me. But I digress... You may also call a hot dog a bunwich because that's just a stupid, made up word with no pedigree. But sandwich?
And while we're at it, open faced sandwiches are not sandwiches, either. That's just a frickin' oversized canape, fer Pete's sake. Going down that road just opens the door to include pizzas and flatbreads into the sandwich realm. Madness.