Field help (EECNAT) 

This is the economic information on the performed transaction. The nature of the transaction is used in the Intrastat.
This information is initialized using the physical flows where it can be modified. This information can also be accessed from some financial flows (sales invoices and credit memos).
The transaction nature is initialized according to the setup of the correspondence table for the Movement rules and natures. This table is used to associate an EU rule and an EU transaction nature to each flow type. This setup can be adjusted by rule, country and group of companies.