Key signature A minor as each accidental may be notated explicitly as required, or the piece may be modal or atonal. An example is Bartók's Piano Sonata, which has no fixed key and is highly chromatic. If not bound by common practice conventions, microtones can also be notated in a key signature; which microtonal symbols are used depends on the system. The common practice period conventions are so firmly established that some musical notation programs have been unable to show nonstandard key signatures until recently. The use of a one-flat signature developed in the Medieval period, but signatures with more than one
Key signature the signature. In the major key with four flats (B E A D), for example, the penultimate flat is A, indicating a key of A major. In this case each new scale starts a fifth "below" (or a fourth above) the previous one. A key signature is not the same as a key; key signatures are merely notational devices. They are convenient principally for diatonic or tonal music. The key signature defines the diatonic scale that a piece of music uses without the need for accidentals. Most scales require that some notes be consistently sharped or flatted. For example, the