[sdiy] modular synth "standards"

[Kenneth Martinez]

Working on my first DIY synth project here, and I'm trying to make it follow
"standards" where possible (and yes, I know there's plenty of them to choose
from).  I realize there's a variety of physical connectors for modules, but
I'm wondering mainly about electrical characteristics.  If I want to be able
to interconnect with various commercially-produced modules at a later date,
looks like I should use a +15V/-15V power supply; and 2 grounds (as with
MOTM).

So, what else?   What are "typical" p-p audio signal levels in the system?

My VCOs will scale using 1V/octave, although some other circuits are
0.5V/octave, so I'm basically using 0 to +10V CV.  I've seen some mention of
negative CV, but am not sure how common that is...?


p.s. I'm not a collector, so the commercial modules I refer to are those that
can be purchased today from active companies.