[COOT] Coot - Difference Map for Water

[SUBSCRIBE CCP4BB Anonymous]

Hi,

I would like to use Coot to generate a difference map to validate my waters.
 I see Coot has the ability to generate a difference map from two different
.MTZs.  I have my original .MTZ from the phasing output but which .MTZ do I
use for the second map?  How do I make this happen with Coot?

Thanks,
Jon