Field Application Documents (FADs) provide an explanation of the application of the relevant standard (e.g. ISO/IEC 17025, ISO/IEC 15189, etc) and include a description of the NATA accreditation procedures applied to each particular field or program. Facilities must comply with this document, all relevant clauses of the relevant standard, the NATA Rules and relevant statutory requirements. Additional information relating to specific areas of testing, or changes or additions to accreditation requirements, or policies may be issued from time to time in the form of Technical or Policy Circulars. These shall supersede any previous requirements where indicated. The FAD must therefore be read in conjunction with all of these references and are included in the NATA Accreditation Requirements (NAR).