I am working on a paper looking at movement in both a normal and psychiatric population. In the 3dvolreg help it is written that the columns of the dfile will contain: n, roll, pitch, yaw, dS, dL, dP, rmsold, and rmsnew. It is also listed that roll corresponds to the I-S axis, pitch R-L and yaw is A-P. My question is, does the I-S correspond to an X axis, R-L = y axis and A-P = z axis? Also, would I correspond to the negative aspect of the X axis and S the positive aspect of the X, etc? I have looked at the message board and the afni main page as well as the Cox article from 1999 but can not find this information. Also, the roll pitch and yaw seem to be different in SPM compared to afni.