[Chimera-users] Default contour level in Volume Viewer

Hello all, How is the default contour level in the Volume Viewer calculated when you first open up a .mrc file? I've tried the average density, and the root-mean-square of all voxels, but both do not match Volume Viewer's default level. I've tried looking here [ http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/volumeviewer/framev...] for documentation on this, but it does not mention it. Thanks, Mike