Hope this works. Here's part two:Good example, Justa. The reason "Blackbird" works so well as a tuning...and ESPECIALLY, intonation guide, is there are lots of unisons. If your guitar plays in tune when there are three or four "Gs" (low, high, fretted and open) then you know the saddle and nut are set correctly. It's not always thus. Even on very expensive Martins, the intonation can be out, and you either get 'em fixed or play out of tune.
Rick