Country: Use ISO country code (e.g. FR, BE, DE), not full name.
VAT Number: Not mandatory, but required by most AP (Accounts Payable) systems. Format FR + 11 digits.
Code E-Invoicing: Used for AP systems (Chorus Pro / PDP). This is the routing address provided by the client for e-invoicing (often SIRET or SIRET_ServiceCode). Example: 852943117_85294311700014. Leave empty if not provided. Stored for reference and embedded in Factur-X BuyerReference when you use E-facture FR.