This will vary by BAPI. In most cases, you will get a RETURN structure with status codes and other information. Look for the BAPI documentation.
I hope you are using the Developer to create the outbound map. If so, it will provide the output parameters automatically from the BAPI lookup.
Again, see the SAP Adapter Guide for details.
Howard
#Adapters-and-E-Standards#webMethods#Integration-Server-and-ESB