This could get very confusing. Easy to remember...the Cajun a'cordeen most used is in the key of "C"...therefore each fiddle string is tuned down one note so the key of "D" is then"C". ie, the fiddler plays in the key of "D" and it sounds like the key of "C"....cause that's what it is. The alternate tho rare a'cordeen keys are "G" "F" "D" "A". Except for "F" which is "G" in the re-tune, standard tuning is used. For the auto-harp and dulcimer start a new thread....please!