U+1D139 "𝄹" Musical Symbol Quindicesima Bassa Unicode Character

U+1D139 "𝄹" Musical Symbol Quindicesima Bassa is a notation mark used in musical scores to instruct the performer to play the indicated notes two octaves lower than written, functioning as the lower counterpart to the more common quindicesima alta symbol. Its name comes from the Italian word for "fifteenth," referring to the interval of two octaves (15 diatonic scale steps), and it appears as a horizontal line with the number "15" positioned below the staff to avoid clutter from ledger lines. This symbol is part of the Musical Symbols block in Unicode, supporting precise engraving of complex piano and orchestral music where extreme register shifts are required without altering the staff notation itself.