Base Standards

measures, measuring instruments, and measuring transducers that serve to check other measuring devices and that are certified as models. Base standards are subdivided into grade 1 types, grade 2 types, and so on. The grade 1 base standards are certified by a comparison with the prototype standard, or, in the absence of a prototype, by gauging the standard to be certified according to indirect measurements using known physical parameters. Grade 2 base standards are certified by a comparison with grade 1 base standards, and so on. On the broadest level, the purpose of all base standards is the calibration of all working standards in the country.