Original sentence: An example of this would be after a flute solo.If there were three flute parts, but only two are required to play, a2 would be marked.If there were three instruments to a part, but one part needs to be louder than the others, the other parts may show a2.If, later on, all three flutes were then needed, a3 would be marked, or unis if they were all to play the same.In music, a2 is an abbreviation for a due or à deux.It is generally marked after a previous marking of solo, when multiple performers are looking off of a single sheet of music.It would also be used in smaller ensemble music, for example, a quartet.The marking signifies that two instruments are to play the designated part in unison.This would be used when quieter instruments would be playing against a full orchestra, instructing more instruments to play the same part to balance the sound
Edited sentence: " or "2." or Io and IIo) indicate that only a single player should play and the other remains tacet."a2" indicates that both players should play the notes indicated, while "primo" and "secondo" (often abbreviated to "1.In music, a2 is an abbreviation for a due (Italian) or à deux (French); literally, for two.It is generally seen in scores and parts where two players of the same instrument share a staff.The marking signifies that on a staff that normally carries parts for two players, both players are to play the single part in unison