I am not a structural analyst, but rather an optical analyst trying to understand what my structural analyst has given me.
He is reporting 6DOF motion of a ridig body point due to thermal expansion in a global coordinate system we both agree to.
He claims RX is rotation about X-axis, RY is rotation about Y-axis, and RZ is a rotation aout the Z-axis. Of course translation is what it is and must have happened first. But the order of rotations is important to get the correct final answer. He won't explicitely say for sure if it's Rx then Ry, then Rz, but he thinks it is. I wonder if these aren't in fact direction cosines.
Ultimately, I just care how to calculate the normal to the surface.