Editing Module:Convert/documentation/conversion data/introduction (section)

==Conversion factors and physical constants==

The values for most of the conversion factors used by [[Template:Convert]] come from international and national standards documents:
* {{cite book |author=Organisation Intergouvernementale de la Convention du Mètre |title=The International System of Units (SI) |url=https://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf |publisher=[[Bureau International des Poids et Mesures]] |orig-year=2006 |year=2014 |accessdate=26 June 2018}} This documents links to the NIST document in section 4.2 "Other non-SI units not recommended for use".
* {{cite book |last1=Thompson |first1=Ambler |last2=Taylor |first2=Barry N. |title=Guide for the Use of the International System of Units (SI) - Publication 811, 2008 Edition, 2nd printing |date=November 2008 |url=https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication811e2008.pdf |publisher=[[National Institute of Standards and Technology]], U.S. Department of Commerce |accessdate=26 June 2018}}

The NIST document gives conversion factors correct to 7 places. Factors in bold are exact. If exact factors have more than 7 places, they are rounded and no longer exact. This convert module replaces these rounded figures with the exact figures. For example, the NIST document has 1 square mile = 2.589 988 E+06 square meters. The convert template has 1 square mile = 2,589,988.110336 square meters.

Values for the fundamental physical constants come from the ''NIST Reference on Constants, Units, and Uncertainty'', either the 2010 or the 2014 version. The 2018 version is in preparation. While the articles on the units should be updated as the new versions come out every four years, the few more [[significant figures]] provided are probably not necessary for the way this template is used. 
* {{cite web |title=CODATA 2010 Table at NIST |url=https://physics.nist.gov/cuu/pdf/all_2010.pdf}} From {{cite journal |last1=Mohr |first1=Peter J. |last2=Taylor |first2=Barry N. |last3=Newell |first3=David B. |title=CODATA recommended values of the fundamental physical constants: 2010 |journal=Reviews of Modern Physics|volume=84 |issue=4 |year=2012 |pages=1527–1605 |doi=10.1103/RevModPhys.84.1527}}
* {{cite web |title=CODATA 2014 Table at NIST |url=https://physics.nist.gov/cgi-bin/cuu/Category?view=pdf&All+values.x=57&All+values.y=9}} From {{cite journal |last1=Mohr |first1=Peter J. |last2=Newell |first2=David B. |last3=Taylor |first3=Barry N. |title=CODATA recommended values of the fundamental physical constants: 2014 |journal=Reviews of Modern Physics |volume=88 |issue=3 |year=2016 |doi=10.1103/RevModPhys.88.035009}}

Definitions for additional historical measures are found in sources such as
* {{cite book |last=Fenna |first=Donald |title=A Dictionary of Weights, Measures, and Units |year=2002 |publisher=Oxford University Press |isbn=978-0-19-107898-9}}