Key signature key signatures showing sharps or flats on both octaves for notes which fall within the staff. An accidental is an exception to the key signature, applying only to the measure and octave in which it appears. Although a key signature may be written using any combination of sharp and flat symbols, the most common series of thirteen homogeneous key signatures—ranging from six flats to six sharps, with each successive flat or sharp placed on the note a perfect fifth below or above, respectively, the previous one—is assumed in much of this article. A piece scored using a single diatonic key
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