Hi, I've tried both of the methods of naming an output file in the book environment. \bookOutputSuffix works fine.
I've used \bookOutputName and output-filename in the paper block as shown
below:
*\book { \paper { output-filename = "Comin-Home-Baby_Tenor-1" }
%\bookOutputName "Comin-Home-Baby_Tenor-1" \header {*
Laurie Savage
