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 or a "sharp" key signature. The key signatures with seven flats () and seven sharps () are rarely used because they have simpler enharmonic equivalents. For example, the key of C major (seven sharps) is more simply represented as D major (five flats). For modern practical purposes these keys are (in twelve tone equal temperament) the same, because C and D are enharmonically the same note. Pieces "are" written in these "extreme" sharp or flat keys, however: for example, Bach's Prelude and Fugue No. 3 from Book 1 of The Well-Tempered Clavier BWV 848 is in C major. The modern