The European Committee for Standardisation (CEN) has issued a standard on e-invoicing that ensures EU-wide standardisation in syntax (rules according to which the computerised system of symbols/characters is formed) and semantics (meaning of the symbols/characters of this system) as a basis for national implementation. The member states can introduce their own standards or formalisation of the standard (so-called CIUS) based on this standard. Conformity to the CEN standard facilitates EU-wide processing.