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
Minor scale based on the accidentals of the "natural" minor scale, not on those of the harmonic or melodic minor scales. For example, a piece in E minor will have one sharp in its key signature because the E natural minor scale has one sharp (F). Major and minor keys that share the same key signature are "relative" to each other. For instance, F major is the relative major of D minor since both have key signatures with one flat. Since the natural minor scale is built on the 6th degree of the major scale, the tonic of the relative minor is