It’s suggested to adjust the existing normative documents, in particular the first version of GOST R 8.596-20xx “State system for ensuring the uniformity of measurements. Metrological assurance for measuring systems. Main principles”. The aim of the proposed adjustment is to legitimate the nuclear power plants complex measuring systems application, taking into account their peculiarities in the sphere of state regulation of ensuring the unity of measurements. Generally complex measuring systems possess all features of the adaptive and intelligent measuring systems, which parameters and algorithms can vary during operation. Therefore, it is proposed for adaptive and intelligent measuring systems and for branched measuring channels, to provide the possibility of dividing into separate measuring components without the whole system or channel approving. The systems and channels measuring components are proposed to be considered as approval measuring instruments, which interaction is regulated by certified measurement techniques. When selecting the boundaries of the measuring system or channel, it is proposed to provide the possibility to be guided by the reasonability of the sorting the technical means or operations involved in parameter control as metrologically significant. In addition, it is proposed to introduce a statute that allows to avoid the type approving of the “degenerate” systems consisting of one or more simple channels formed only by the measuring means.