Word of the day
octave clef
A symbol used to indicate that the music notated should be performed at a pitch level either an octave higher or an octave lower than is indicated by the normal version of that clef. Octave clefs include the G octave clef (octave_treble_clef) and the f octave clef (octave_bass_clef).
The need for these clefs comes from the instruments and voice types that read music printed on the staff (with a minimum of ledger lines), but in actuality, sound an octave higher or lower than where the notes are written. Examples would include the male tenor voice (sounding an octave lower than written) and the piccolo (sounding an octave higher than written). If this were notated correctly, the performer would be reading notation with an excessive number of ledger lines.
See more about clefs in the Appendix.