1) Staff addition 
A ledger line or leger line is used in Western musical notation to notate pitches above or below the lines and spaces of the regular musical staff. A line slightly longer than the note head is drawn parallel to the staff, above or below, spaced at the same distance as the lines within the staff (see Figure 1). Although ledger lines are found occas...
small line for placing notes above and below The stave
In music a ledger line is a line added above or below the staff to extend its compass.
[n] - a short line
leger line noun a short line; a notation for extending the range above or below the staff