ArcPad 6 supports on-the-fly coordinate transformation from one coordinate system to another coordinate system. When using ArcPad with GPS, the coordinates from the GPS receiver are always in WGS84 format, but our local data is using Hong Kong 1980 Grid system, we can make use of this function in ArcPad 6 to avoid converting the data to WGS84 to use with GPS. However, we need to edit the apDatums.dbf file located in \Program Files\ArcPad\System to add transformation details and parameters used in Hong Kong in order to activate this function. This tool helps you to edit the apDatums.dbf file within ArcPad 6 interface so that users can change settings during fieldwork in case of errors in existing parameters, comparing results or data preparation.