Greg,many years ago a record distributor clerk in Germany with a moderate level of knowledge got the task to divide the whole world of folk music into not too many subsets of about equal number of records for easy labeling in all shops.
He came up with the following seven categories: Dubliners, Irish, Scottish, German, Balkan and Southern Europe, Dylan, Carribean and South American.
Since then, only the label 'world music' has been added to cover Africa, Asia and unclear cases. Little shops with few (folk) records are allowed to go down to three different labels: Celtic, German, World Music.
Even if what I have told is an invention the shops do as if it was true. Since then, I have found Barachois (Canada) under 'world', 'Irish', 'Celtic', 'Brittany' Watersons (England) under 'Scottish', 'Irish', 'Celtic', Tom Paxton under 'Dylan', Chieftains under 'Dubliners', Swedish fiddle music under 'Balkan', music from the Hebrides under 'Irish', Christy Moore under 'Pop and Rock',....
Even allowing for truly difficult cases for categorising as Eric Bogle or Peggy Seeger, it's a shame.
Wolfgang