Key signature sometimes called "standard key signatures". Other scales are written either with a standard key signature and use accidental as required, or with a nonstandard key signature. Examples of the latter include the E (right hand), and F and G (left hand) used for the E diminished (E octatonic) scale in Bartók's "Crossed Hands" (no. 99, vol. 4, "Mikrokosmos"), or the B, E and F used for the D Phrygian dominant scale in Frederic Rzewski's "God to a Hungry Child". The absence of a key signature does not always mean that the music is in the key of C major /
Key signature musical "Seussical" by Flaherty and Ahrens also has several songs written in these extreme keys. Key signatures can be further extended through double sharps and double flats (for example, a piece in the key of G major can be expressed with a double sharp on F and six sharps on the other six pitches). As with the seven-sharp and seven-flat examples, it is rarely necessary to express music in such keys when simpler enharmonic examples can instead be used (in the case of G, the same passage could be expressed in A with only four flats). The key signature may