The simplest scales are the pentatonic ones - they have only 5 notes. The blues scales have 6 notes. "m" stands for minor and "M" stands for major (the difference between a minor scale and its major correspondent - containing the same notes - is three frets. For example, the major correspondent of F#-minor is A-major, the major correspondent of A-minor is C-major). The blue bullets show the note to be added in order to transform a pentatonic scale to a blues one: |