Hierarchy of Standards of Weights and Measures
International Prototype Kept at Sevres, France
National Prototype Kept at NPL, New Delhi
National Standards Kept at NPL, New Delhi
Reference Standards Kept at RRSLs at Ahmedabad, Bangalore, Bhubaneswar, Faridabad, Guwahati & IILM at Ranchi
Secondary Standards Kept at State Standard Labs
Working Standards Kept at Inspectorial units