%lilypond input for "Extender_Line.ly"
\version "2.10.25"
\header { 
	title = "Extender lasting until the end of the note"
	composer = "Reinhold Kainhofer"
}

sopMusic = \relative c'' {
  c1~ | c2 r2 | c1~ c2 r2 | 
}

altoMusic = \relative c' {
  \repeat unfold 6 {e8 g} r2 |
  e8\melisma g \repeat unfold 5 {e8 g}\melismaEnd r2 |
}

sopLyrics = \lyricmode {  Ah __ ah __ }
altLyrics = \lyricmode { La, la, la, la, la, la, la, la, la, la, la, la, la. __ }

\markup { \fill-line { \override #'(line-width . 80)
\justify-string #"Extender lines over melismata in lyrics usually last until the last note of the melisma. Normally, this is sufficient to indicate to the singer how long to hold a given note. However, when the last note is a very long note and other voices sing many notes during it, it is extremely important that the singers hold the melisma exactly. For this reason, in several printed scores the extender lines are then extended to the end of last note of the melisma to indicate how long to sing the note. 

As an example, take the following trivial snipplet. Soprano needs to hold the c for six beats, but the extender line is much shorted, thus some sopranos might be tempted to stop that note earlier!

How can I make the extender line really last until the end of the melisma (in this case until the 12th \"la\" of the altos?"} }

\score {
  \context ChoirStaff <<
    \new Lyrics = sop { s1 }
    \context Staff <<
      \context Voice = sopranos { << \voiceOne \sopMusic >> }
      \context Voice = altos { << \voiceTwo \altoMusic >> }
    >>
    \new Lyrics = alt { s1 }
    
    \context Lyrics = sop \lyricsto sopranos \sopLyrics
    \context Lyrics = alt \lyricsto altos \altLyrics
  >>

  \layout { }
}