English to Russian Science Metrology эталоны и калибровка измерительного оборудования

речь идет о калибровке измерительного оборудования. Вроде бы что-то насчет прослеживаемости к эталонам Национального института стандартов и технологий, но смысл предложения в целом ускользает.
Контекст:
Whenever practical, measuring equipment should have a rated accuracy of about 10 percent of the tolerance being measured. Similarly, standards used to calibrate measuring equipment and instruments should have appropriate capability. As a general rule, and within state-of-the-art or economic limitations, the standards of measurement systems used should have a tolerance no greater than 10 percent of the allowable tolerance of the equipment being calibrated. Through the proper selection of standards of appropriately higher accuracy levels, the equipment should be maintained in a state of calibration with the measurement of parameters traceable to the National Institute of Standards and Technology or other acceptable levels of reference.