Extensions of the Fully Diminished 7 chord: Hopefully you know by this point that if you number the notes of a major scale as 1234567& octave, you know that every other note (1357) create the basic chord tones. The notes you skipped (246) create the extensions once considered an octave higher. Diminished 7 chords also have extensions. They exist as one whole step above each chord tone. For example, the extensions of C Eb Gb Bbb are D F Ab and B (natural); obviously another diminished 7 chord a whole step higher. By all means use this tip!! While soloing over dim 7 make certain you use the extensions- so much more interesting!