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 sometimes is this change indicated with a change of key signature; if not, the passage in the second key will not have a matching key signature. The Toccata and Fugue in D minor, BWV 538 by Bach has no key signature, leading it to be called the "Dorian", but it is still in D minor; the Bs that occur in the piece are written with accidentals. Keys which are associated with the same key signature are called relative keys. When musical modes, such as Lydian or Dorian, are written using key signatures, they are called "transposed modes". Exceptions to common-practice-period