Flatting and cold-calling

What's the difference please, if any?

I read Getting Started in Hold'Em by Ed Miller in one sitting last night, and the only phrase in there that neither myself nor Roger had encountered before was Cold Calling. We thought that was walking into businesses without an appointment and trying to sell them something!

Presumably cold calling means two or more people have bet before you, whereas flatting might imply just one person?

Maybe flatting is when you call where you have a hand and could re raise but you want them to lead out again, and cold calling is when you're calling a bet with nothing? I'm not sure just guessing.


***EDIT*** After referring to google, it seems cold calling is in fact calling when there is more than one bet in a single action. I.E. "If one opponent bets, and another raises, and you call, you have cold called."