Iain Boyd writes in Strathspey message 63756, on 15 Feb 2013:  "The Vallin collections are not RSCDS publications so I would tend NOT to use RSCDS-speak, and assume that the reels of three are just what they are described as - 'tandem reels' without the leading dancers swapping over. Unfortunately, John Morris died last year (I think) so there is no way that we can ask him."