3 texidoc = "Span bars draw only in between staff bar lines, so setting those to transparent shows bar lines between systems only.
8 \notes \relative c' \context StaffGroup = groupie <
9 \context Staff = SB { a1 a1 a1}
10 \context Lyrics = LB \lyrics <
14 \context Staff = SC { f1 f1 f1}
19 BarLine \override #'transparent = ##t