The rules are very limited. Any track that has been officially released (on a legitimate label) in any country is acceptable. If a song has been selected, a different artist/band that has released a version of the same song is acceptable provided that no members of the band performed in any version that has been already picked. I will be commissioner and will have the sole discretion of what is acceptable and what is not. I plan to exclude as few tracks as possible, so I will be as lenient as I can.