What is this tiny door on the left on the big door? I've nevee figured out how to use it so it's just kind of there. Someone said it's a conventional oven, and there is a button that says "Conv" next to the dials. Can anyone tell me what it is and how it works? What I can make in it? I just bought this oven used and I've never used one before. You can tell it needs a good cleaning, is there anything special I need to clean this part? Or can I just treat it like the rest of the oven? Sorry I'm asking a million questions. Google is confusing me and I have no experience with this.