From defining the units to their realization: the new “mises en pratique”
This revision was governed by the principle that “realizing an SI unit” means that the measurement is to be understood as defined by means of “primary methods”, and that influence parameters on the respective measurement uncertainty as well as possible corrections must be specified.
In the new, fundamentally revised mise en pratique for the SI unit of length, the meter, the reference to the primary measurands was, for example, clearly developed for the first time and the achievable measurement uncertainty as well as the influence parameters and corrections to be considered were named. Furthermore, methods for the secondary realization of the meter in the field of nanometrology were included in three guidelines of the Consultative Committee for Length. These methods were based on the work carried out in the scope of the International Avogadro Cooperation Project, among other things.