Re: [Lilypond-auto] Issue 2745 in lilypond: clef change confuses manual key signature

[lilypond]

Updates:
        Labels: Needs-design

Comment #3 on issue 2745 by address@hidden: clef change confuses manual key  
signature
http://code.google.com/p/lilypond/issues/detail?id=2745

I have looked through the other accidental functions, and all this is a  
mess.  From a mail I wrote on this topic  
<URL:http://lists.gnu.org/archive/html/lilypond-user/2012-08/msg00279.html>:

Ok, consider me annoyed now.  Yes, we have some snippets documenting
this sort of thing, but what is it even supposed to mean?

The actual accidental _code_ knows two kinds of accidental entries: one
_without_ octave entry for the key signature, and one _with_ octave
entry _and_ bar/measure position for signifying a locally changed key
signature by a particular accidental in the music with given note and
octave and time.

The actual code does not try making sense of a _key_ signature entry
_with_ octave (and consequently without bar/measure position).  And what
is a key signature with octave location actually supposed to mean?  Do
we need an accidental for a note in key signature but one octave higher,
or not?

So I fail to make _any_ sense of your example.  If I had to guess, I'd
say the octave specifications are there for overriding the default
octaves chosen by the key signature engraver, but without being fixed to
a certain octave concerning their effect on the music.

However, with _that_ interpretation, a clef change like you propose
above leads to accidentals displayed up in the sky in ledger line
domain.  What's the key engraver to do in this case?  Transpose the
whole octave-enriched key signature down by entire octaves (thus keeping
the arrangement of the scale) until it starts making sense again?  Leave
it in the sky with ledger lines?  Without?

What is your expectation?  For what kind of music and situation is this
useful?

I have the suspicion that this is a documentation problem more than  
anything else: I don't really see the sense in a key signature with octave  
specifications.