Provides a summary of the system, gives rules on how derived units may be formed, and affords a selection of multiples and sub-multiples of units for application in the various fields of technology. It also includes reference to certain non-SI units of measurement which at this stage have been recognized for use in association with SI units. An annex gives an extensive list of SI units with decimal multiples and sub-multiples, and other units or names of units which may be used for various fields of technology, including requirements of ionizing radiation. The point is given as the preferred decimal marker and the letter L as the preferred symbol for litre.