The UBL Format

UBL (Universal Business Language) was developed by OASIS (Organization for the Advancement of Structured Information Standards). Like xCBL it is a library of standard electronic XML business documents. UBL 2.0 was released in 2006 and since then Denmark has mandated by law the use of this format for all invoices to the public sector. PEPPOL, the Pan-European Public Procurement OnLine project initiated by the European Commission, is aiming at expanding market connectivity and interoperability between eProcurement communities. PEPPOL's infrastructure and services for eProcurement uses standardised electronic document formats based on UBL 2.1 which was released in November 2013.

Two-phase validation model

UBL 2.1 assumes a two-phase validation model. In the first validation phase, the UBL document is checked for structure and vocabulary against a standard UBL 2.1 XSD schema using a generic XSD validator. In the second validation phase code the content is validated against business rules and code lists.

Subsets of UBL

The PEPPOL Business Interoperability Specifications (BIS) are based on the UBL 2.1 standard while specifications of the OIOUBL format used within the Danish NEMHANDEL/EasyTrade network are based on UBL 2.0. Also the internal format used within TRADESHIFT is based on UBL 2.0.