Hi All. I know how to id from a key signature, but what about a chord sheet with no key sig? I know in general many songs begin and end with the root, but this rule is not set in stone. Considering that sharps/flats can be thrown in is there any foolproof way to do this? I am starting to use the Nashville Numbers System so that I can jump keys on the fly if need be, but I want to make sure I am using the degrees of the correct scale for this.