This CEN Technical Specification (TS) specifies the mapping between the semantic model of an electronic invoice, included in EN 16931-1 and the UBL 2.1 syntax (ISO/IEC 19845). For each element in the semantic model (including sub-elements or supplementary components such as Identification scheme identifiers) it is defined which element in the syntax is to be used to contain its information contents. Any mismatches between semantics, format, cardinality or structure are indicated.