I'd like to be able to convert between two Canadian vertical coordinate systems: CGVD28 and CGVD2013. The staff at Natural Resources Canada have a conversion grid which is in ".byn" format (Canadian Geodetic Survey binary geoid file), but have offered to convert to another format if ArcGIS can't read/use it. I don't have a handle on the different methods & formats supported, and which would be most appropriate. Melita Kennedy, what can I tell them? Or - is this file something ESRI already has in hand?