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 vice versa, the old key signature is cancelled with the appropriate number of naturals before the new one is inserted; but many more recent publications (whether of newer music or newer editions of older music) dispense with the naturals and simply insert the new signature. Similarly, when a signature with either flats or sharps in it changes to a smaller signature of the same type, strict application of tradition or convention would require that naturals first be used to cancel just those flats or sharps that are being subtracted in the new signature before the new signature itself is written;