How to define the names of separate \book output files

[Patrick Schmidt]

Hi all,

I'm using several \book blocks in one .ly file. This results as 
expected/desired in several output files such as foo.pdf, foo-1.pdf, foo-2.pdf, 
etc. Is there a way to define the name of the output files in the .ly file? 
Thus it wouldn't be necessary to rename the output files to something like 
"complete-score.pdf", "instrument1.pdf", "instrument2.pdf", etc.

Thanks for any hint!
patrick