Hi

I am trying to display a depth bar on the extended profile that starts from 0. Not to show the altitude, but only the depth of the cave relative to the entrance.

This is not a problem if I use the FIX command like:
  centerline
    cs long-lat
    fix 1 11:22:33.3 22:33:44.4 1000 # fix point 1to the WGS coordinates and altitude

The thing is that I don't want to put 0 for an altitude because it seems useful to have the real altitude for some 3D, overlays, etc

So I would like to use FIX with the altitude, but on the extended to see the cave depth starting from 0.
I tried with some combinations of grid-origin like this, but I still see the altitude in the depth bar:
  layout xelev
    grid bottom
    cs long-lat
    grid-origin 0 0 0 m

Is there a way to do it?

Thanks

Vladimir