If a point is raised that distracts from the matter in hand, then it needs to be addressed if only to get it out of the way. It is reasonably clear, I'd have thought, that my comment was made in response to Dave Rowlands, not the original questioner.

As to establishing terms of reference, you will of course know that the term 'slow air' as used in Ireland is frequently explained as an instrumental development of the singing tradition; no longer dependent on vocal range, considerable expansion becomes possible. Though a common definition and helpful so far as it goes, I certainly would not consider it all-inclusive. Jack Campin's first post in this discussion is pretty comprehensive in that regard.