Though I've played guitar, and a few other strings, a number of years, I must admit this is an entirely new (to me) method of fretting!
(Alexander Vynograd's arrangement for an eight string guitar of Bach's BWV639 [the 1713 chorale Ich ruf' zu dir, Herr Jesu Christ, which was used as the theme for Tarkovsky's 1972 version of Lem's Solaris].)
