It was the term "warm up act" that you threw out there. I wasn't sure if you were implying that you think they're the same thing. I guess that can happen from time to time, but from what I've seen, I'd say that the cover bands are typically very small acts playing on their own, usually at very small venues. But if a band only covers one or two songs like Chef Jim mentioned, that can happen at pretty much any level, from a big time band like Van Halen all the way down to that group of kids next door in the garage.