Haven't been able to read last 60 postings, so I'm coming at marion's question fresh. As reagards minor key tunes, some generaliations are possible, for fiddle tunes at least(songs tunes are different). I am referring to the areas where I have done research, English, Scottish and Irish tunes.(I dont use the term Celtic in this context, it contains certain possible historic assumptions which may be misleading or just plain wrong). There are no hard and fast rules, but you won't go far wrong if you say: Bminor tunes are Aeolian. Eminor tunes are mixed, with a preponderance of Dorian tunes, but a fair amount of Dorian/Aeolian(variable 6th) or Aeolian. Tunes in Aminor are nearly all Dorian. The differencesbetween the modes is not huge( the 6th of the scale is only very rarely emphasised on the beat) so different musicians may have the same tune in different modes, and the versions could be played together without too much clash. Tunes with a sharp 7th(eg the song version of Greensleeves) are fairly rare in the fiddle tradition, which interelates with pipes and whistles rather than keyboards and lutes (where those sort of harmonic implications are easier to cope with). So country fiddlers playing Greensleeves would play a minor seventh throughout, with a sharp 6th,( in Aminor). Song tunes are another thing, of course.A singer can sing in Aminor or Bminor with equal ease, depending on voice range.So these sort of differnces cant arise.