Musical note indicated by placing the symbols in the key signature, which then apply implicitly to all occurrences of corresponding notes. Explicitly noted accidentals can be used to override this effect for the remainder of a bar. A special accidental, the natural symbol , is used to indicate an unmodified pitch. Effects of key signature and local accidentals do not accumulate. If the key signature indicates G, a local flat before a G makes it G (not G), though often this type of rare accidental is expressed as a natural, followed by a flat () to make this clear. Likewise (and more
Theoretical key G♯ major) may have to be notated completely differently. Theoretical key In music theory, a theoretical key or impossible key is a key whose key signature has at least one double-flat or double-sharp. Double-flats and double-sharps are often used as accidentals, but placing them in the key signature (in music that uses equal temperament) makes the music generally impractical to read. For example, the key of G major is a key of this type, because its corresponding key signature has an F (on its leading-tone). An equal-tempered scale of G major comprises the same pitches as the A major scale,