NIST Administrative Manual, Subchapter 4.09
Transmittal Date - 12/21/93
APPENDIX D
USE OF METRIC UNITS
In accordance with the Metric Conversion Act of 1975 as amended by Section
5164 of the Omnibus Trade and Competitiveness Act of 1988 and as required
by related provisions of the Code of Federal Regulations, the National
Institute of Standards and Technology (NIST) uses the modern metric system
of measurement units (International System of Units; abbreviation: SI)
in all publications. When the field of application or the special needs
of users of NIST publications require the use of non-SI units, the values
of quantities are first stated in SI units and the corresponding values
expressed in non-SI units follow in parentheses. Exceptions to this policy
require the prior approval of the Director.
NIST Special Publication 330, The International System of Units (SI),
identifies a number of additional units as follows:
--units in use with the International System;
--units used with the International System but whose values in SI units
are obtained experimentally (the electronvolt and the unified atomic mass
unit); and
--units in use temporarily with the International System.
(See tables 8, 9, and 10 of the 1991 edition of SP 330.)
All of these units may be used as if they were SI units.
The NIST policy stated above applies to the expression of measured and
calculated values of quantities. It is frequently necessary to use measurement
units in a nominal or descriptive sense to characterize materials or objects.
In such cases, metric units are not required; e.g., it is acceptable to
refer to a "36-inch pipeline" or a "half-inch drill" without the use of
the corresponding metric values and units.
During the preparation of manuscripts, authors should refer to: A Guideline for the Use of the International System of Units: The Modernized Metric System, NIST SP 811.