is a European standard for a core invoice and is published in a number of parts:
- Semantic data model of the core elements of an electronic invoice (the European Norm).
- List of syntaxes that comply with EN 16931.
- Methodology for syntax bindings of the core elements of an electronic and syntax bindings to ISO/IEC 19845 (UBL 2.1) and to UN/CEFACT XML.
- Guidelines on interoperability of electronic invoices at the transmission level.
- Guidelines on the use of sector or country extensions in conjunction with EN 16931.