ISO 9000 addresses to which the certificate refers. An ISO 9001 certificate is not a once-and-for-all award but must be renewed at regular intervals recommended by the certification body, usually once every three years. There are no grades of competence within ISO 9001: either a company is certified (meaning that it is committed to the method and model of quality management described in the standard) or it is not. In this respect, ISO 9001 certification contrasts with measurement-based quality systems. The ISO 9000 standard is continually being revised by standing technical committees and advisory groups, who receive feedback from those professionals who
ISO 31 ISO 31 ISO 31 (Quantities and units, International Organization for Standardization, 1992) is a deprecated international standard for the use of physical quantities and units of measurement, and formulas involving them, in scientific and educational documents. It is superseded by ISO/IEC 80000. The standard comes in 14 parts: A second international standard on quantities and units was IEC 60027 . The ISO 31 and IEC 60027 Standards were revised by the two standardization organizations in collaboration (, ) to integrate both standards into a joint standard "ISO/IEC 80000 - Quantities and Units" in which the quantities and equations used with