The survey benchmark monuments that I am using publish elevations as NAVD88 (geoid 18) or Ortho-elevation. Is it correct that the RS2 units when set up on monument as a base require elevation to be the ellipsoidal elevation. If so does anyone know how to convert the Ortho-elevation (NAVD88) to the ellipsoid elevation (NAD83) or WGS84 ellipsoid? My work is in Utah, USA.