Re: ChoirStaff produces DrumStaff in 2.5.30

[Imruska]

> It would be helpful if you'd post the contents of your \score block.

\score {
 \context ChoirStaff <<
 \context Voice = discantusNotes << \global \discantusNotes >>
 \context Lyrics = discantusLyrics \lyricsto discantusNotes
        { discantusLyrics }
 \context Voice = altusNotes << \global \altusNotes >>
 \context Lyrics = altusLyrics \lyricsto altusNotes { \altusLyrics }
 \context Voice = tenorNotes << \global \tenorNotes >>
 \context Lyrics = tenorLyrics \lyricsto tenorNotes { \tenorLyrics }
 \context Voice = bassusNotes << \global \bassusNotes >>
 \context Lyrics = bassusLyrics \lyricsto bassusNotes { \bassusLyrics } >>

\layout {
...
}
}

This worked fine in 2.4.x. I took this from the manual Chapter 3.5.1
Ancient Notation where it started as \context StaffGroup = choirStaff
and I changed it into \context ChoirStaff

> I think I encountered this a couple weeks back too. It worked fine
> once I explicitly created Lyrics contexts and assigned them to
> explicitly-created Staff contexts which were then assigned to the
> ChoirStaff.  At the time I didn't experiment further because it Just
> Worked(TM).

Finally I was able to solve this problem by the way suggested by you. 
Fortunately, I once saw in a score how the single staves have been 
created outside the \score block, and were only put together within it.

So the solution is: outside the \score block

discantusstaff = \context Staff = "discantus" <<
        \global
        \context Voice = "discantus"
        { \discantusNotes }
        \context Lyrics = discantusLyrics
        \lyricmode <<
        \lyricsto "discantus"
        { \discantusLyrics }
        >>
        >>

the same for altus, tenor and bassus then

within the \score block

\context ChoirStaff <<
        \discantusstaff
        \altusstaff
        \tenorstaff
        \bassusstaff
        >>

I believe, however, that the fact Lilypond 2.5.30 creates a
DrumStaff where it is explicitly told to create a ChoirStaff is a bug.

Well, the Lilypond manual was not exactly helpful in this matter.
At the sections 3.4.1 and 3.4.2 "SATB vocal score" and "SATB vocal score
and automatic piano reduction" it has examples only for a score where 
the 4-part vocal music is notated in 2 staves, one for women's voices, 
one for men's voices, and not in an individual staff for each part, so I 
disregarded them completely.

I was further confused by Chapter 6.3.7 System Start Delimiter, which
mentions GrandStaff, StaffGroup and Staff. It says that you can use a 
Bracket as a SSD with StaffGroup where the barlines are connected 
throughout the staves. It does not mention ChoirStaff, so I feared this 
option has been removed from Lilypond 2.5.x. (I did not know 2.5.x, as 
up till now I have been using 2.4.x, I installed 2.5.29, then 2.5.30 
about a week ago.)

Imre