For questions about 8va (all'ottava) and related notation.
The symbol: 8va [or just 8], is an abbreviation of all'ottava (alta), which is Italian for "at the octave (higher)".
When placed above a passage of notes spanned with a dashed line, this symbol indicates that these notes are to be played an octave higher than written. The end of the dashed line is sometimes accompanied by the more explicit: loco, meaning "at place".
Similarly, 8va b. (all'ottava bassa) placed below a passage of notes indicates these notes are to played an octave lower. The popular alternative 8vb is often used instead, but this is not good Italian.
15ma (quindicesima), 22ma (ventiduesima), etc. can theoretically be used for notes written respectively two or three octaves above/below notated, but these have limited practical value.
The related notation: col 8va (coll'ottava) is sometimes used in keyboard music. This indicates the written notes are to be played together with the notes an octave above.
