This directory is intended to hold a variety of standalone horizontal datum grid shift files from a variety of sources. Please either document the files within this README or provide a corresponding .txt file documenting it. nad83_2002.ct2: CTable2 file produced with HTDP for transforming from NAD83 2002 to WGS84 2002 http://trac.osgeo.org/proj/wiki/HTDPGrids nad83_2010.ct2: CTable2 file produced with HTDP for transforming from NAD83 2010 to WGS84 2002 http://trac.osgeo.org/proj/wiki/HTDPGrids chenyx06etrs.gsb.gz: NTv5 gridshift file for transforming CH1903 to WGS84. See CHENyx06-Distribution.pdf and http://trac.osgeo.org/proj/ticket/145