ledger linen.Music（名词）【音乐】Notes above and below a staff are placed on ledger lines. Notes F (left) and B (right) are shown on ledger lines.Precision Graphics
A short line placed above or below a staff to accommodate notes higher or lower than the range of the staff.加线：加于五线谱上方或下方用于记录高于或低于五线谱音域的一条短线
