Outbound process requires two configuration settings: 1) Establish a link between message type, IDoc type, and...
IDoc extension( transaction WE82).
2) In Partner profile Outbound parameters specify message type, Idoc type, Basic IDoc type, and Extension type. (transaction WE20).
Inbound process needs only one configuration setting to make the IDoc extension known to the system. Establish a link between Message type, IDoc type, and IDoc extension(WE57).