The Open Data Services ODBC driver must know where to find the resources DLL for each data source. The GatewayResource keyword in ODBC.INI gives the file path to the specific DLL to use. If the gateway resource filename is of the form ODS*.DLL, and if it is found in the \WINDOWS\SYSTEM directory, the Open Data Services ODBC setup program will know to list the gateway as a choice during setup.