Key signature key signatures showing sharps or flats on both octaves for notes which fall within the staff. An accidental is an exception to the key signature, applying only to the measure and octave in which it appears. Although a key signature may be written using any combination of sharp and flat symbols, the most common series of thirteen homogeneous key signatures—ranging from six flats to six sharps, with each successive flat or sharp placed on the note a perfect fifth below or above, respectively, the previous one—is assumed in much of this article. A piece scored using a single diatonic key
Avoid note Avoid note In jazz theory, an avoid note is a scale degree considered especially dissonant relative to the harmony implied by the root chord, and is thus better avoided. In major-key tonality the avoid note is the fourth diatonic scale step, or 11th, which is a minor ninth above the 3rd of the chord, and thus very harsh. In melody it is usually avoided, treated as a "scale approach note" or passing note, or sharpened. It is not available in harmony. The available tensions for a dominant seventh chord are 9, 11, and 13. In minor harmony the sixth scale