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 (known as CIUS, Core Invoice Usage Specification) based on this standard. Conformity to the CEN standard facilitates EU-wide processing.