The SAP gateway can be from Release 2.1l, 2.2C or 3.0 onwards. Working with type E is only possible with Release 3.0D onwards.
Sample entry in the saprfc.ini file:
DEST = RFCEXT
TYPE = <E (or R): server will be started by (or is already registered at) SAP-GW>
GWHOST = <host name of the SAP gateway, e.g. hs0311>
GWSERV = <service name of the SAP gateway, e.g. sapgw53>
TPHOST = <host name of the RFC server program, e.g. hs0311>
TPNAME = <name of the RFC server program, e.g. /rfctest/srfcserv>
The parameter mode in RfcOpen must be set to RFC_MODE_PARAMETER as usual.