Grass Valley NewsEdit XT v.5.5 - Manual (Page 210)

Chapter 11 Creating Video Effects (Option)
208 Digital News Production
Moving the picture along its x-axis within the source space makes it appear to
move diagonally and 'out' relative to the screen because the rotated global
channel creates z-axis movement relative to the screen.
Moving the picture along its x-axis within the target space makes it appear to
move diagonally across the screen because there is no z-axis change. Because
there are three coordinate systems in this scenario you can also move the target
space along its x-axis to create the same diagonal movement with the picture.
Finally, moving the target space along its x-axis relative to the screen moves
the picture horizontally left to right across the screen.