Properties of the IDocs representation:
Original IDoc type name: The original IDoc type name is taken by default when the original IDoc file is imported, and it can be different from the Structure name in TDM.
Original IDoc extension (optional): If the source IDoc has an extension, this extension is appended to the Structure name to form a unique name.
Original IDoc message type (optional): If you specify the IDoc message type in this field, this type is used as the default type when an IDoc instance is written.
The "Original IDoc type name" and "Original IDoc extension" (if one exists) properties are both taken automatically from the source IDoc.