Standards: documents that contain technical specifications (or other precise criteria) to be used consistently as rules, guidelines, or definitions of characteristics, to ensure that materials, products, processes and services are fit for their designed purpose. Standardisation bodies aim to enhance harmonisation so as to diminish trade barriers, promote safety, allow interoperability of products, systems and services, and promote common technical understanding. National bodies include: Association francaise de normalisation (AFNOR), American National Standards Institute (ANSI), British Standards Institution (BSI), China State Bureau of Quality and Technical Supervision (CSBTS), Deutsches Institut for Normung (DIN) or Standardiseringen i Sverige (SIS). The European bodies include: European Committee for Standardisation (CEN), the European Committee for Electrotechnical Standardisation (CENELEC), and the European Telecommunications Standards Institute (ETSI). International bodies include: International Electrotechnical Commission (IEC) and the International Organisation for Standardisation (ISO)