This fretboard diagram features six horizontal circled numbers that represent the six strings (low to high, left to right) and the vertical chord numbers are five frets anywhere on the fretboard. The numbers in the circles show the note intervals situated around a common six-string barre chord, sixth string root. For example, this could be viewed as the note intervals around the A major or A minor chord shapes played at the 5th fret. The first line of circled numbers (7, 3,6, 9, #4/b5, 7) are those intervals found at the 4th fret, as related to an A barre chord. It’s a powerful visual source; wherever you place the R (root) on the fretboard (with the two R’s on the sixth and first strings at the 5th fret to make an A chord), all these intervals will then fall into place around them.