Hi, I have two questions regarding the command "vop subtract" with the option "minRMS". 1st question) In the help page the option minRMS is defined as: "the min RMS option can be used to scale othermap automatically to minimize the root-mean-square sum of the resulting (subtracted) values at grid points within the lowest contour of othermap." Does this mean that the value that appears in the "Volume viewer" window and labeled as "Level" is used to create a contour and all the grid pints inside this counter are used to compute the scale factor? 2nd question) If I understand the command, minRMS assume that the maps (let us called them V1 and V2) are related by a multiplicative factor. That is V1 = V2 * f where f is a scalar In my case V1 = V2 * f1 + f2 that is, both maps are related by a multiplicative factor (f1) plus and additive factor (f2). Is there any chimera command that compute the average of a volume so I can force both volume to have the same average? Thanks in advance. Roberto