The term does not cover composed popular music that has been taken over ready-made by a community and remains unchanged, for it is the re-fashioning and re-creation of the music by the community that gives it its folk character.

Like so much in the 1954 definition one suspects it's an academic fantasy of a rusticity entirely uninfluenced by the outside world. In other words, it's an aesthetic consideration of authenticity on a par with GEFF.