(Cheryl of the Clue Crew chimes in about musical notation.)   It's the bookkeeping term for the lines above and below the musical staff
[DOC] [TLE] Staff (music) - Wikipedia [PAR] In Western musical notation, the staff, or stave is a set of five horizontal lines and 
four spaces ... For example, the treble clef puts the G above middle C on the 
second line.