 Notation of tuba, trombone, and euphonium parts always use ledger lines below the bass staff, and never the "8va bassa" notation .When music for bass clef instruments, such as the cello or trombone, goes several ledger lines above the bass clef, the tenor clef is used; if it were to go even higher than practical in tenor clef, the notes may be notated in treble clef, or in the case of trombone, alto clef.A ledger line is also used to support a half rest or whole rest where there are multiple voices on one staff and such a rest is forced above or below the staff.