Qus: What is the purpose of Default processing Rule ?
If a document matches more than one processing rule, Trading Networks uses the first Processing rule it encounters. As a result, the order in which you maintain your processing Rules is important because Trading Networks checks for a matching processing rule in that order. Keep rules with specific criteria before rules with general criteria. You should Also set up a default processing rule that you want Trading Networks to use "when a Document does not match any of the other processing rules. Place the default-processing rule last in the list".