Unified Codes For SI Units

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This dataset shows the table of base Units. Any of the fundamental units of length, mass, time, electric current, thermodynamic temperature, amount of substance, or luminous intensity in the International System of Units, consisting respectively of the meter, kilogram, second, ampere, kelvin, mole, and candela.

Complexity

The base units shown in this dataset are used to define all the unit atoms of The Unified Code for Units of Measure according to its grammar and semantics. There are five columns titled “name,” “kind of quantity,” “print,” “c/s,” and “c/i.” The name is the full (official) name of the unit. The official symbol used in print this is listed in the column “print” “C/s,” and “c/i” list the symbol in the case sensitive and the case insensitive variants respectively. Only the columns titled “c/s,” and “c/i,” are normative. Full name and print symbol are defined by other bodies and are out of scope of The Unified Code for Units of Measure. The selection of base units and the particular order are not normative. Any other basis B’ that generates an isomorphic group of units is conformant with The Unified Code for Units of Measure. If the other base B’ generates a different system of units U’ it conforms to The Unified Code for Units of Measure only if there is an homomorphism that maps U’ onto U. Base units must be metric units only. Special units cannot be base units.

As can be seen the base system used to define The Unified Code for Units of Measure is different from the system used by the Système International d’Unités (SI) The SI base unit kilogram has been replaced by gram and the mole has been replaced by the radian that is defined dimensionless in the SI. Because of the latter change, the Unified Code for Units of Measure is not isomorphic with the SI.

The replacement of the kilogram is trivial. In order to bring syntax and semantics in line we can not have a unit with prefix in the base. We need a valid unit of mass before we can combine it with the prefix “kilo-” This change does not have any effect on the semantics whatsoever. The base unit kilogram is one of the oddities of the SI: if the gram would have been chosen as a base units the CGPM (General Conference on Weights and Measures) could have saved the rather annoying exception of the prefixing rules with the kilogram. At times where we have to multiply the wavelength of excited krypton-86 atoms by 1650763.73 to yield one meter, it seems trivial to divide the prototype of the kilogram by thousand to yield a base unit gram.

The rationale for removing the mole from the base is that the mole is essentially a count of particles expressed in a unit of very high magnitude (Avogadro’s number). There is no fundamental difference between the count of particles and the count other things.

The radian has been adopted as the base unit of plane angle α to facilitate the distinction from the solid angle Ω by the relation Ω = α2 and to distinguish rotational frequency f from angular velocity ω = 2 π · rad · f.

Date Created

2014-03-07

Last Modified

2017-03-08

Version

2017-03-08

Update Frequency

Annual

Temporal Coverage

N/A

Spatial Coverage

World

Source

John Snow Labs => Regenstrief Institute, Inc

Source License URL

John Snow Labs Standard License

Source License Requirements

N/A

Source Citation

N/A

Keywords

Terminal Symbols, Unit System, Unified Code for Units of Measure, Units of Measures, SI Units, Prefixes and Units, Vocabulary, Units of Measurement, Units of Measurement List, Unit Converter

Other Titles

International Organization Of Standardization Quantities And Units, System International Units

Name Description Type Constraints
Name_Of_The_UnitThe name is the full (official) name of the unit.string-
Used_In_PrintThe official symbol used in printstring-
Case_SensitiveShows the Sensitivity of the Case Letterstring-
Case_InsensitiveShows the Insensitiveness of the Case Letterstring-
Definition_ValueDefinition Valuestring-
Definition_UnitDefinition Unitstring-
Is_A_Metric_UnitCombinations of a unit symbol with a prefix symbolboolean-
Kind_of_QuantityKind of Quantity to be measuresstring-
ValueMeasurement Valuestring-
RemarksShows which unit is used in which categorystring-
Name_Of_The_UnitUsed_In_PrintCase_SensitiveCase_InsensitiveDefinition_ValueDefinition_UnitIs_A_Metric_UnitKind_of_QuantityValueRemarks
bel lg(1 1) truelevel Other Legacy Units
exa EEX1 × 1018Unified Code for Terminal Symbols
kibiKiKiKIB1024Prefixes used in Information Technology
gram gGmass Unified Code for Measuring Base Units
peta PPT1 × 1015Unified Code for Terminal Symbols
kilo kK1 × 103 Unified Code for Terminal Symbols
yotta YYA1 × 1024Unified Code for Terminal Symbols
zetta ZZA1 × 1021Unified Code for Terminal Symbols
giga GGA1 × 109 Unified Code for Terminal Symbols
mega MMA1 × 106 Unified Code for Terminal Symbols