Instrument in score block?

[Maarten Deen]

Is it possible to define headers (like instrument) in the score context? I've 
tried, and nothing comes up.

Background: I play trumpet and use Lilypond to transpose music. You have parts 
in F, A, E flat, whatever, and my trumpets are tuned in B flat or C.

So what I do is I write the score in an lyi file and include that in a ly file 
that does the transposing.

So I get something like below. Two book parts, one with suffix C (so the 
filename is score-C.pdf) and one with suffix Bes. In the \score I do the 
transposing. And of course because I do the transposing there, I can only set 
the instrument there. It is important that you specify which trumpet to take, 
otherwise you're a full note off ofcourse.

But as I said, this does not work. Are there other options?

\book {
        \bookOutputSuffix "C"
        
        \score {
                \transpose c bes, { \partI }
                \header { instrument = "Trumpet in C" }
                \layout { ragged-last = ##f }
                
        } %% \score

} %%\book

\book {
        \bookOutputSuffix "Bes"
        
        \score {
                \transpose bes bes { \partI }
                \header { instrument = "Trumpet in Bes" }
                \layout { ragged-last = ##f }
                
        } %% \score

} %%\book


Regards,
Maarten