Does anybody know how to do this:
Change ALL the elevations in the drawing by adding 153m. That is, if the text shows an elevation of -0.352 you need to add 153 to this so that it will say 152.648. You can add 153m to each elevation one at a time... but this would take an enormous amount of time. It would be much easier to load up the lisp routine that I provided and change the elevations all at once.