roll  = rotation about the I-S axis }
pitch = rotation about the R-L axis } degrees CCW
yaw   = rotation about the A-P axis }
dS  = displacement in the Superior direction  }
dL  = displacement in the Left direction      } mm
dP  = displacement in the Posterior direction }

* The 12 parameters are, in the order used on the 1dApar2mat command line
  (the same order as output by 3dAllineate):
   x-shift         in mm
   y-shift         in mm
   z-shift         in mm
   z-angle (roll)  in degrees (not radians!)
   x-angle (pitch) in degrees
   y-angle (yaw)   in degrees
   x-scale         unitless factor, in [0.10,10.0]
   y-scale         unitless factor, in [0.10,10.0]
   z-scale         unitless factor, in [0.10,10.0]
   y/x-shear       unitless factor, in [-0.3333,0.3333]