The NTEP program is administered through the National Conference on Weights and Measures (NCWM).
NTEP requires industry to submit prototype weighing devices for evaluation to determine whether or not it meets the uncertainties which are related to tolerances associated with the intended final use in the marketplace. All devices sold in the United States for "legal for trade" purposes must pass these evaluations.
The NIST Force laboratory serves as a technical resource to the NTEP program by providing advice on requirements and test procedures to industry and NCWM Specifications and Tolerance Committee via the National Type Evaluation Technical Committee Weighing Sector and by performing type evaluation tests of load cells from 100 lbf through 120,000 lbf.
For more details see NCWM's webpage about obtaining NTEP Certification.