split staves/lyrics

[Erik Sandberg]

Hi again,

The example with SATB in my previous email will hereby be completed with 
another even harder issue: Suppose that first all voices are unison, and that 
then _everyone_ is separated for one bar. In standard rigorous SATB notation 
this would be notated as:

        lalala bar lalala 
SA staff==================
        lalala baz lalala
        lalala baa lalala
TB staff==================
        lalala foo lalala 

But this is often in non-rigorous notation written more like

               bar 
SA staff==================
               baz
        lalala     lalala
               baa 
TB staff==================
               foo

but where the lines "baz" and "baa" overlap the lalala line, like this (using 
an ascii art magnifying glass):

               | \
               |_/   /
               | \  /-
|       /\     |_/ /
|      /  \     _
|     /----\   | \
|___ /      \  |_/   /
               | \  /-
               |_/ /

I fear that it would take quite some restructuring to make this possible.. But 
somehow it feels like a logical possibility, and something similar could also 
be useful for staffs: Consider the example where 1st and 2nd violins are 
unison almost everywhere. During one bar they are different, and we want to 
split the staff into two for this bar only. I would find it logical to notate 
it like this (though I am not sure whether I ever have seen it):

                |---------------|
                |---------------|
                |----vln1-------|
                |---------------|
----------------|---------------|-----------------
----------------|               |-----------------
--unison--------|               |-----------------
----------------|               |-----------------
----------------|---------------|-----------------
                |---------------|
                |----vln2-------|
                |---------------|
                |---------------|

I.e., the unison staff is centered, and possibly partially vertically 
overlapped by, the two vln* staves. I guess it's basically the same problem 
as with lyrics, to be able to redefine the set of staves in the middle of a 
system (I have seen no signs from Lilypond of being able to do this, vertical 
space seems to be allocated per system).

I do not have any suggestions of how this could be notated, I just want to 
raise this as an open question. How far away is it to be able to do stuff 
like this?

Finally, I must say that I don't know if this at all is a standard kind of 
notation. All I know is that I _have_ seen it for lyrics.

Erik