Musical note standardised at 440 Hz, lying in the octave containing notes from C (middle C) to B. The lowest note on most pianos is A, the highest C. The MIDI system for electronic musical instruments and computers uses a straight count starting with note 0 for C at 8.1758 Hz up to note 127 for G at 12,544 Hz. A written note can also have a note value, a code that determines the note's relative duration. In order of halving duration, they are: double note (breve); whole note (semibreve); half note (minim); quarter note (crotchet); eighth note (quaver); sixteenth note (semiquaver).;
Whole note rest may also be used in music of free rhythm, such as Anglican chant, to denote a whole measure. A whole note (American) or semibreve (British) is a musical note represented by a hollow oval note head—like a half note (or "minim")—and no note stem (see Figure 1). Its length is equal to four beats in time, that is the whole measure (or bar). Most other notes are fractions of the whole note. Half notes last for one half the duration of the whole note, quarter notes (or "crotchets") last for one quarter the duration, and a double whole note