Trebles( I think the term triples is also used) means playing a triplet with the bow on a crotchet when playing a reel. (It may mean other things to other people, that was what I was talking about). It is sometimes notated as threee quavers with a line and a 3 over them, sometimes as two semi-quavers and a quaver. The third note is often taken in one bow with the note that follows.