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).;
Grace note such time as audio recording was implemented, and even then, only a composer's personal or sanctioned recording could directly document usage. As either an appoggiatura or an acciaccatura, grace notes occur as notes of short duration before the sounding of the relatively longer-lasting note which immediately follows them. This longer note, to which any grace notes can be considered harmonically and melodically subservient (except in the cases of certain appoggiaturas, in which the ornament may be held for a longer duration than the note it ornaments), is called the "principal" in relation to the grace notes. A Grace note or