I'm trying to understand the conversion from RAS (freesurfer surface coordinate) to volume space (x, y, and z.. According to Graham Wideman documentation here http://www.grahamwideman.com/gw/brain/fs/coords/fscoords.htm (if it is not outdated), Right is negative x, Anterior is positive z, and Superior is positive y. 

Just to double check, usign mri_info on a sample T1.mgz in one subject I get this ras to voxel transform:

-1   0    0   126.944

 0   0   -1   135.16

 0   1    0   110.6

 0   0    0    1

Assuming we have correctly set the (0, 0, 0), and we can extract R A and S (respectively) coordinates using C++ or Python code it means: Right is negative x, Anterior is negative z, and Superior is positive y (conflicting coordinates are in vold). Am I missing anything here, or coordinate systems have changed from the probably outdated documentation? Thanks in advance for any input on this rather confusing point. 

All the best,

Arman