A false easting of 500000 m is assigned to the central meridian (24° east), so eastings are always positive. Conversion from geographical coordinates in GRS80 to a projection in HGRS87 is supported by PROJ with appropriate parameters. The conversion is performed with the following code (shell command line): proj +proj=tmerc +lat_0=0 +lon_0=24 +k=0.9996 +x_0=500000 +y_0=0 +ellps=GRS80 +towgs84=-199.87,74.79,246.62,0,0,0,0 +units=m +no_defs While HGRS87 is still widely used for most civilian uses, it is partly replaced by the new Hellenic Terrestrial Reference System 2007 or HTRS07 (SRID=96758). HTRS07, which was specified for the Hellenic Positioning System (HEPOS) project, is GPS based and is compatible with European Terrestrial Reference System 1989 (ETRS89). HTRS07 is currently used for the cadastral surveys.