In an effort to save people time through my mistakes I thought I would bring to light a slight "bug" in the VDatum command line executable. The documentation is pretty good, but misses an important point. There is no cmd line switch to turn off the "use gis id" function, so if the ascii input file is missing a row identifier field (as a GDAL converted file will not have), it will not process any of the file and report that all cells are "invalid". it took me a while to figure this out so I thought I would share...