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 between one and seven, applied in this order: . A mnemonic device often used to remember this is "Father Charles Goes Down And Ends Battle." The key note or tonic of a piece in a major key is immediately above the last sharp in the signature. For example, one sharp (F) in the key signature of a piece in a major key indicates the key of G major, the next note above F. (Six sharps, the last one being E (an enharmonic spelling of F) indicate the key of F major, since F has already been sharped in the key