Is there anyway to control individual filenames? I'm losing data

[Patrick Horgan]

For example, from O Magnum Mysterium I get 5 midi files, one for the 
choral rendition, then one for each voice.  They are named:
O_Magnum_Mysterium.midi     soprano
O_Magnum_Mysterium-1.midi alto
O_Magnum_Mysterium-2.midi tenor
O_Magnum_Mysterium-3.midi bass

Then the second book, O_Magnum_Mysterium-1 and it generates a midi file

O_Magnum_Mysterium-1.midi for the choir which wipes out the alto midi file.


I'd much rather have soprano.midi, alto.midi, tenor.midi, bass.midi, and 
choir.midi.
Is there anywhere within the \midi{} sections that I can set a file name?

Patrick