MOTM

Hi MOTM'ers!

Quick question for y'all, 

Does the MOTM system use a clean/dirty GND? The two GND pins suggest 
it, but perhaps not?. 

If there is a separate dirty gnd pin, which of the two pins is 
considered the dirty gnd? (The one next to -V or the one next to +V?)

Continuing, if there is a dual gnd setup: Do all MOTM modules respect 
this division of the return paths?

Thank you,

Randal