Folks,while trying to tidy up ly/engraver-init.ly a bit (which seems to have experienced some rank growth over the years) I stumbled upon:
\context { \Staff \type "Engraver_group" \name "DrumStaff" \alias "Staff" % (etc.) }That's the only instance of a context definition that contains _both_ a parent context type (\Staff) _and_ \type "Engraver_group".
Is that correct? I don't know enough about the inner workings to judge reliably.
Lukas