Not quite sure what GUEST Rabbie means here, but note that RB himself didn't actually claim "ALS" as his own, stating that he got the words and air from "an old man's singing"; the quotation goes something like, "The oldest and by far the best set is this, which was never in print before until I got it from an old man's singing". I think the page in question is in the Glenriddel Collection in the NLS, Edinburgh.