Universal key fractions (e.g. an A natural in the scale above becomes ) or, more commonly in written text, by inserting an accidental before the number (e.g. the same note becomes 5 or 4). In music theory aimed towards jazz and popular music, all triads are represented by upper case numerals, followed by a symbol to indicate if it is not a major chord (e.g. "m" for minor or "ø" for half-diminished): When representing the triads rooted in a minor key, accidentals are used to indicate the chromatic alteration from the assumed major key roots indicated by numerals that don't have accidentals:
Key signature the signature. In the major key with four flats (B E A D), for example, the penultimate flat is A, indicating a key of A major. In this case each new scale starts a fifth "below" (or a fourth above) the previous one. A key signature is not the same as a key; key signatures are merely notational devices. They are convenient principally for diatonic or tonal music. The key signature defines the diatonic scale that a piece of music uses without the need for accidentals. Most scales require that some notes be consistently sharped or flatted. For example, the