I have to agree with pdq - if Doc isn't folk , therre's no such thing.      I'm sure Pete Seeger would agree. Doc really isn't "bluegrass" but bis guitar style has influenced bluegrass as much as Bill Monroe's mandolin and Earl Scruggs' banjo. But then again, I'd consider Monroe and Scruggs as icons of American folk music. Doc, Bill, and Earl have much stronger trasditional roots than Pete, and once again, I'm sure Mr. Seeger would bw the first to agree.