(a) Results of calibrations and other tests are issued to the customer as formal reports entitled, “National Institute of Standards & Technology Report of Calibration,” “National Institute of Standards & Technology Report of Test,” or “National Institute of Standards & Technology Report of Analysis,” as appropriate. Copies are not supplied to other parties except under applicable Federal law. Whenever formal certification is required by law, or to meet special conditions adjudged by NIST to warrant it, a letter will be provided certifying that the particular item was received and calibrated or tested, and identifying the report containing the results.

(b) NIST reports of calibration generally include in sentence form a statement of the uncertainty attached to the numerical values reported. Limits of uncertainty usually comprise an estimate of systematic error plus a value of imprecision. Details on how these estimates are arrived at are in many cases included in the calibration report. Additional information may be found in SP 250.

(c) The NIST practice is to express data given in calibration or test reports in the SI or International System of Units. The International System of Units (SI) was defined and given official status by the 11th General Conference of Weights and Measures, 1960. A complete listing of SI units is presented in detail in NIST SP 330. The NIST will express data in SI units unless this makes communication excessively complicated. For example, commercial gage designations, commonly used items identified by nominal dimensions, or other commercial nomenclatures or devices (such as drill sizes, or commercial standards for weights and measures) expressed in customary units are an exception from this practice. However, even in such instances, when practical and meaningful, SI and customary units may be given in parallel. Users of NIST calibration services may specify the units to be used in the calibration, especially for commercial devices and standards using customary units or units having some legal definition.