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
Key signature the next-to-last note – is played as an A even though the A in the key signature (the last sharp sign) is written an octave lower). In a score containing more than one instrument, all the instruments are usually written with the same key signature. Exceptions include: The convention for the notation of key signatures follows the circle of fifths. Starting from C major (or equivalently A minor) which has no sharps or flats, successively raising the key by a fifth adds a sharp, going clockwise round the circle of fifths. The new sharp is placed on the new key's