Micro-: Difference between revisions
Adding local short description: "Metric system unit prefix", overriding Wikidata description "prefix denoting 10 to the −6th power" |
→Symbol encoding in character sets: The CJK Compatibility block contains square forms of some Japanese katakana measure and currency units. {{Unichar|3343}} corresponds to {{lang|ja|マイクロ}} {{transl|ja|maikuro}}. |
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'''''Micro''''' (Greek letter '''μ''' |
'''''Micro''''' ([[Greek letter]] '''μ''', [[Mu (letter)|mu]], non-[[Italic type|italic]]) is a [[metric prefix|unit prefix]] in the [[metric system]] denoting a factor of 10<sup>−6</sup> (one [[millionth]]).<ref name="Gold">{{SIbrochure8th}}</ref> Confirmed in 1960, the prefix comes from the [[Ancient Greek|Greek]] {{lang|grc|[[wikt:μικρός|μικρός]]}} (''{{lang|grc-Latn|mikrós}}''), meaning "small". |
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It is the only [[International System of Units|SI]] prefix which uses a character not from the [[Latin alphabet]]. In [[Unicode]], the symbol is represented by {{unichar|03BC}} or the legacy symbol {{unichar|00B5}}. The prefix "mc" is commonly used in healthcare or when the character "μ" is not available; for example, "mcg" commonly denotes a microgram.<ref name="ISMP_2021"/> The letter "u" is sometimes used instead of "μ" when non-[[Latin alphabet|Latin]] characters are not available. |
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==Examples== |
==Examples== |
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* Typical [[bacteria]] are 1 to 10 [[micrometre]] |
* Typical [[bacteria]] are 1 to 10 [[micrometre|micrometer]] (1–10 μm) in diameter. |
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* [[Eukaryote|Eukaryotic cells]] are typically 10 to 100 |
* [[Eukaryote|Eukaryotic cells]] are typically 10 to 100 micrometers in diameter.<ref>''Biology'' by Campbell & Reece, tenth edition. Ch. 6 "A Tour of the Cell". p. 98.</ref> |
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{{SI prefixes (infobox)}} |
{{SI prefixes (infobox)}} |
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==Symbol encoding in character sets== |
==Symbol encoding in character sets== |
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The official symbol for the [[metric prefix|SI prefix]] ''micro'' is a [[mu (letter)|Greek lowercase mu]] (μ).<ref>[https://www.bipm.org/en/measurement-units/si-prefixes Prefixes of the International System of Units], [[International Bureau of Weights and Measures]] (page visited on 9 May 2016).</ref> For reasons stemming from its design, [[Unicode]] has two different character codes for the letter, with slightly different appearance in some fonts, although most fonts use the same [[glyph#Typography|glyph]]. |
The official symbol for the [[metric prefix|SI prefix]] ''micro'' is a [[mu (letter)|Greek lowercase mu]] (μ).<ref>[https://www.bipm.org/en/measurement-units/si-prefixes Prefixes of the International System of Units], [[International Bureau of Weights and Measures]] (page visited on 9 May 2016).</ref> For reasons stemming from its design, [[Unicode]] has two different character codes for the letter, with slightly different appearance in some fonts, although most fonts use the same [[glyph#Typography|glyph]]. {{unichar|00B5|MICRO SIGN}} ({{keypress|Alt|0181}}) is in the "Latin-1 Supplement" range identical to [[ISO/IEC 8859-1]] (since 1987),<ref>(Unicode 1.0, 1991)</ref> residing at this code point also in [[DEC MCS]] (since 1983) and [[ECMA-94]] (since 1985). {{unichar|03BC|GREEK SMALL LETTER MU}} ({{keypress|Alt|956}}) is in the Greek range. According to [[The Unicode Consortium]], the Greek letter character is preferred,<ref>[https://www.unicode.org/reports/tr25 Unicode Technical Report #25]</ref> but implementations must recognize the micro sign as well, for [[Unicode compatibility characters|compatibility with legacy character sets]]. This distinction also occurs in some legacy code pages, notably [[Windows-1253]]. |
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In circumstances in which only the [[Latin alphabet]] is available, [[ |
In circumstances in which only the [[Latin alphabet]] is available, [[International Standards Organization|ISO]] 2955 (since 1974,<ref name="ISO_2955-1974">{{cite book |title=ISO 2955-1974: Information processing - Representations of SI and other units for use in systems with limited character sets |edition=1st |date=1974}}</ref> withdrawn 2001<ref name="ISO_2955-1983">{{cite book |url=http://isotc.iso.org/livelink/livelink/4289384/ISO_2955-1983E_repr_of_SI_units_with_limited_char_sets.pdf?func=doc.Fetch&nodeid=4289384 |title=ISO 2955-1983: lnformation processing - Representations of SI and other units for use in systems with limited character sets |date=1983-05-15 |edition=2nd |chapter=Table 2 |access-date=2016-12-14}} [http://www.bgu.ac.il/~averbukh/ISO_2955-1983E.pdf]</ref>), [[Deutsches Institut für Normung|DIN]] 66030 (since 1980<ref name="DIN_66030_1980">{{cite book |title=DIN 66030: Darstellungen von Einheitennamen in Systemen mit beschränktem Schriftzeichenvorrat |language=de |edition=1st |date=1980}}</ref><ref name="Computerwoche_1981_DIN">{{cite journal |title=Neue Normen für die Informationsverarbeitung |language=de |journal=[[Computerwoche]] |date=1981-01-09 |url=http://www.computerwoche.de/a/neue-normen-fuer-die-informationsverarbeitung,1184901 |access-date=2016-12-14 |url-status=live |archive-url=https://web.archive.org/web/20161214025700/http://www.computerwoche.de/a/neue-normen-fuer-die-informationsverarbeitung%2C1184901 |archive-date=2016-12-14}}</ref>) and [[British Standards Institution|BS]] 6430 (since 1983) allow the prefix <code>μ</code> to be substituted by the letter <code>[[u]]</code> (or even <code>[[U]]</code>, if lowercase letters are not available), as, for example, in <code>um</code> for <code>μm</code>, or <code>uF</code> for <code>μF</code>, or in the common abbreviation <code>UC</code> for [[microcontroller]] (μC). |
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Similarly, capacitor values according to the [[RKM code]] defined in [[International Electrotechnical Commission|IEC]] 60062 (since 1952) can be written as <code>4u7</code> (or <code>4U7</code>) instead of <code>4μ7</code> if the Greek letter <code>μ</code> is not available. |
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The [[CJK Compatibility]] block contains square forms of some Japanese [[katakana]] measure and currency units. |
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{{Unichar|3343}} corresponds to {{lang|ja|マイクロ}} {{transl|ja|maikuro}}. |
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==Other abbreviating conventions== |
==Other abbreviating conventions== |
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In some [[health care]] institutions, house rules deprecate the standard symbol for [[microgram]], "μg", in prescribing or chart recording, because of the risk of giving an incorrect dose because of the misreading of poor handwriting.<ref name="Tietz_PT2241">{{Citation |last1=Burtis |first1=Carl A. |last2=Ashwood |first2=Edward R. |last3=Bruns |first3=David E. |year=2012 |title=Tietz Textbook of Clinical Chemistry and Molecular Diagnostics |isbn=978-1455759422 |edition=5th |url=https://books.google.com/books?id=BBLRUI4aHhkC&pg=PT2241 |postscript=.}}</ref> The two alternatives are to abbreviate as "mcg"<ref name="Tietz_PT2241"/><ref name="ISMP_2021"/> or to write out "microgram" in full (see also [[List of abbreviations used in medical prescriptions]]). |
In some [[health care]] institutions, house rules deprecate the standard symbol for [[microgram]], "μg", in prescribing or chart recording, because of the risk of giving an incorrect dose because of the misreading of poor handwriting.<ref name="Tietz_PT2241">{{Citation |last1=Burtis |first1=Carl A. |last2=Ashwood |first2=Edward R. |last3=Bruns |first3=David E. |year=2012 |title=Tietz Textbook of Clinical Chemistry and Molecular Diagnostics |publisher=Elsevier Health Sciences |isbn=978-1455759422 |edition=5th |url=https://books.google.com/books?id=BBLRUI4aHhkC&pg=PT2241 |postscript=.}}</ref> The two alternatives are to abbreviate as "mcg"<ref name="Tietz_PT2241"/><ref name="ISMP_2021"/> or to write out "microgram" in full (see also [[List of abbreviations used in medical prescriptions]]). The alternative abbreviation may be ambiguous in rare circumstances in that ''mcg'' could also be read as a ''micrigram'', i.e. 10<sup>−14</sup> g; however the prefix ''[[micri-|micri]]'' is not standard, nor widely known, and is considered obsolete. This deprecation, focused on avoiding incorrect dosing in contexts where handwriting is often present, does not extend to all health-care contexts and institutions (for example, some clinical laboratories' reports adhere to it, whereas others do not<ref name="Tietz_PT2241"/>), and in [[physical sciences]] research, "μg" remains the sole official abbreviation. |
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In medical data exchange according to the [[Health Level 7]] (HL7) standard, the μ can be replaced by u as well.<ref name="HL7_2015"/> |
In medical data exchange according to the [[Health Level 7]] (HL7) standard, the μ can be replaced by u as well.<ref name="HL7_2015"/> |
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<ref name="HL7_2015">{{cite web |title=Commonly Used UCUM Codes for Healthcare Units |date=2015-11-21 |publisher=HL7 Deutschland e.V. |url=https://download.hl7.de/documents/ucum/ucumdata.html |access-date=2022-12-24 |url-status=live |archive-url=https://web.archive.org/web/20221006180404/https://download.hl7.de/documents/ucum/ucumdata.html |archive-date=2022-10-06}}</ref> |
<ref name="HL7_2015">{{cite web |title=Commonly Used UCUM Codes for Healthcare Units |date=2015-11-21 |publisher=HL7 Deutschland e.V. |url=https://download.hl7.de/documents/ucum/ucumdata.html |access-date=2022-12-24 |url-status=live |archive-url=https://web.archive.org/web/20221006180404/https://download.hl7.de/documents/ucum/ucumdata.html |archive-date=2022-10-06}}</ref> |
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<!-- <ref name="HL7_2022">{{cite web |title=Commonly Used UCUM Codes for Healthcare Units |date=2015-11-21 |publisher=HL7 Deutschland e.V. |url=https://howtotypesymbols.com/how-to-type-mu-micro-symbol-in-word-and-mac/ |access-date=2023-01-14 |url-status=live |archive-url=https://web.archive.org/web/20221006180404/https://download.hl7.de/documents/ucum/ucumdata.html |archive-date=2022-10-06}}</ref> --> |
<!-- <ref name="HL7_2022">{{cite web |title=Commonly Used UCUM Codes for Healthcare Units |date=2015-11-21 |publisher=HL7 Deutschland e.V. |url=https://howtotypesymbols.com/how-to-type-mu-micro-symbol-in-word-and-mac/ |access-date=2023-01-14 |url-status=live |archive-url=https://web.archive.org/web/20221006180404/https://download.hl7.de/documents/ucum/ucumdata.html |archive-date=2022-10-06}}</ref> --> |
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<ref name="ISMP_2021">{{cite web |title=ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations: Abbreviations for Doses/Measurement Units |date=2021-02-05 |work=Recommendations |publisher=[[Institute for Safe Medication Practices]] (ISMP) |url=https://www.ismp.org/recommendations/error-prone-abbreviations-list |access-date=2022-12-24 |url-status=live |archive-url=https://web.archive.org/web/20221224213621/https://www.ismp.org/recommendations/error-prone-abbreviations-list |archive-date=2022-12-24 |quote=Error-Prone Abbreviations, Symbols, and Dose Designations: |
<ref name="ISMP_2021">{{cite web |title=ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations: Abbreviations for Doses/Measurement Units |date=2021-02-05 |work=Recommendations |publisher=[[Institute for Safe Medication Practices]] (ISMP) |url=https://www.ismp.org/recommendations/error-prone-abbreviations-list |access-date=2022-12-24 |url-status=live |archive-url=https://web.archive.org/web/20221224213621/https://www.ismp.org/recommendations/error-prone-abbreviations-list |archive-date=2022-12-24 |quote=Error-Prone Abbreviations, Symbols, and Dose Designations: μg […] Intended Meaning: Microgram […] Misinterpretation: Mistaken as mg […] Best Practice: Use mcg […]}}</ref> |
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Latest revision as of 12:19, 10 June 2024
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png)
Micro (Greek letter μ, mu, non-italic) is a unit prefix in the metric system denoting a factor of 10−6 (one millionth).[1] Confirmed in 1960, the prefix comes from the Greek μικρός (mikrós), meaning "small".
It is the only SI prefix which uses a character not from the Latin alphabet. In Unicode, the symbol is represented by U+03BC μ GREEK SMALL LETTER MU or the legacy symbol U+00B5 µ MICRO SIGN. The prefix "mc" is commonly used in healthcare or when the character "μ" is not available; for example, "mcg" commonly denotes a microgram.[2] The letter "u" is sometimes used instead of "μ" when non-Latin characters are not available.
Examples
[edit]- Typical bacteria are 1 to 10 micrometer (1–10 μm) in diameter.
- Eukaryotic cells are typically 10 to 100 micrometers in diameter.[3]
Prefix | Base 10 | Decimal | Adoption [nb 1] | |
---|---|---|---|---|
Name | Symbol | |||
quetta | Q | 1030 | 1000000000000000000000000000000 | 2022[4] |
ronna | R | 1027 | 1000000000000000000000000000 | |
yotta | Y | 1024 | 1000000000000000000000000 | 1991 |
zetta | Z | 1021 | 1000000000000000000000 | |
exa | E | 1018 | 1000000000000000000 | 1975[5] |
peta | P | 1015 | 1000000000000000 | |
tera | T | 1012 | 1000000000000 | 1960 |
giga | G | 109 | 1000000000 | |
mega | M | 106 | 1000000 | 1873 |
kilo | k | 103 | 1000 | 1795 |
hecto | h | 102 | 100 | |
deca | da | 101 | 10 | |
— | — | 100 | 1 | — |
deci | d | 10−1 | 0.1 | 1795 |
centi | c | 10−2 | 0.01 | |
milli | m | 10−3 | 0.001 | |
micro | μ | 10−6 | 0.000001 | 1873 |
nano | n | 10−9 | 0.000000001 | 1960 |
pico | p | 10−12 | 0.000000000001 | |
femto | f | 10−15 | 0.000000000000001 | 1964 |
atto | a | 10−18 | 0.000000000000000001 | |
zepto | z | 10−21 | 0.000000000000000000001 | 1991 |
yocto | y | 10−24 | 0.000000000000000000000001 | |
ronto | r | 10−27 | 0.000000000000000000000000001 | 2022[4] |
quecto | q | 10−30 | 0.000000000000000000000000000001 | |
|
Symbol encoding in character sets
[edit]The official symbol for the SI prefix micro is a Greek lowercase mu (μ).[6] For reasons stemming from its design, Unicode has two different character codes for the letter, with slightly different appearance in some fonts, although most fonts use the same glyph. U+00B5 µ MICRO SIGN (Alt+0181) is in the "Latin-1 Supplement" range identical to ISO/IEC 8859-1 (since 1987),[7] residing at this code point also in DEC MCS (since 1983) and ECMA-94 (since 1985). U+03BC μ GREEK SMALL LETTER MU (Alt+956) is in the Greek range. According to The Unicode Consortium, the Greek letter character is preferred,[8] but implementations must recognize the micro sign as well, for compatibility with legacy character sets. This distinction also occurs in some legacy code pages, notably Windows-1253.
In circumstances in which only the Latin alphabet is available, ISO 2955 (since 1974,[9] withdrawn 2001[10]), DIN 66030 (since 1980[11][12]) and BS 6430 (since 1983) allow the prefix μ
to be substituted by the letter u
(or even U
, if lowercase letters are not available), as, for example, in um
for μm
, or uF
for μF
, or in the common abbreviation UC
for microcontroller (μC).
Similarly, capacitor values according to the RKM code defined in IEC 60062 (since 1952) can be written as 4u7
(or 4U7
) instead of 4μ7
if the Greek letter μ
is not available.
The CJK Compatibility block contains square forms of some Japanese katakana measure and currency units. U+3343 ㍃ SQUARE MAIKURO corresponds to マイクロ maikuro.
Other abbreviating conventions
[edit]In some health care institutions, house rules deprecate the standard symbol for microgram, "μg", in prescribing or chart recording, because of the risk of giving an incorrect dose because of the misreading of poor handwriting.[13] The two alternatives are to abbreviate as "mcg"[13][2] or to write out "microgram" in full (see also List of abbreviations used in medical prescriptions). The alternative abbreviation may be ambiguous in rare circumstances in that mcg could also be read as a micrigram, i.e. 10−14 g; however the prefix micri is not standard, nor widely known, and is considered obsolete. This deprecation, focused on avoiding incorrect dosing in contexts where handwriting is often present, does not extend to all health-care contexts and institutions (for example, some clinical laboratories' reports adhere to it, whereas others do not[13]), and in physical sciences research, "μg" remains the sole official abbreviation.
In medical data exchange according to the Health Level 7 (HL7) standard, the μ can be replaced by u as well.[14]
See also
[edit]- Microgram
- Microscope
- Microsecond
- Microwave
- Square micrometre
- List of commonly used taxonomic affixes
References
[edit]- ^ International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN 92-822-2213-6, archived (PDF) from the original on 2021-06-04, retrieved 2021-12-16
- ^ a b "ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations: Abbreviations for Doses/Measurement Units". Recommendations. Institute for Safe Medication Practices (ISMP). 2021-02-05. Archived from the original on 2022-12-24. Retrieved 2022-12-24.
Error-Prone Abbreviations, Symbols, and Dose Designations: μg […] Intended Meaning: Microgram […] Misinterpretation: Mistaken as mg […] Best Practice: Use mcg […]
- ^ Biology by Campbell & Reece, tenth edition. Ch. 6 "A Tour of the Cell". p. 98.
- ^ a b "On the extension of the range of SI prefixes". 2022-11-18. Retrieved 2023-02-05.
- ^ "Metric (SI) Prefixes". NIST.
- ^ Prefixes of the International System of Units, International Bureau of Weights and Measures (page visited on 9 May 2016).
- ^ (Unicode 1.0, 1991)
- ^ Unicode Technical Report #25
- ^ ISO 2955-1974: Information processing - Representations of SI and other units for use in systems with limited character sets (1st ed.). 1974.
- ^ "Table 2". ISO 2955-1983: lnformation processing - Representations of SI and other units for use in systems with limited character sets (PDF) (2nd ed.). 1983-05-15. Retrieved 2016-12-14. [1]
- ^ DIN 66030: Darstellungen von Einheitennamen in Systemen mit beschränktem Schriftzeichenvorrat (in German) (1st ed.). 1980.
- ^ "Neue Normen für die Informationsverarbeitung". Computerwoche (in German). 1981-01-09. Archived from the original on 2016-12-14. Retrieved 2016-12-14.
- ^ a b c Burtis, Carl A.; Ashwood, Edward R.; Bruns, David E. (2012), Tietz Textbook of Clinical Chemistry and Molecular Diagnostics (5th ed.), Elsevier Health Sciences, ISBN 978-1455759422.
- ^ "Commonly Used UCUM Codes for Healthcare Units". HL7 Deutschland e.V. 2015-11-21. Archived from the original on 2022-10-06. Retrieved 2022-12-24.