Is this, then, the only music that can be performed in Folk Clubs?that is for fok club organisers[like yourself] to decide,
and you do this through your booking policy,and also through your choice of residents[,youchoose your residents upon the material they sing and how they perform it]

I could quibble over the details of that but one thing I'm damn sure of, we never ask ourselves or our guests, "Does this material conform to the 1954 Sao Paulo International Folk Music Council definition of folk music?". We may not know much about folk music but we know what we like.