Micro-

Micro- (Greek letter μ or legacy micro symbol µ) 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".

The symbol for the prefix comes from the Greek letter μ (mu). It is the only SI prefix which uses a character not from the Latin alphabet. "mc" is commonly used as a prefix when the character "μ" is not available; for example, "mcg" commonly but confusingly denotes a microgram (mcg could be read by many as micrigram, i.e. 10−14 g). Also the letter u instead of μ is allowed by one of the ISO documents.[2]

Examples:

SI prefixes
Prefix Base 10 Decimal English word Adoption[nb 1]
Name Symbol Short scale Long scale
yotta Y  1024 1000000000000000000000000  septillion  quadrillion 1991
zetta Z  1021 1000000000000000000000  sextillion  trilliard 1991
exa E  1018 1000000000000000000  quintillion  trillion 1975
peta P  1015 1000000000000000  quadrillion  billiard 1975
tera T  1012 1000000000000  trillion  billion 1960
giga G  109 1000000000  billion  milliard 1960
mega M  106 1000000  million 1873
kilo k  103 1000  thousand 1795
hecto h  102 100  hundred 1795
deca da  101 10  ten 1795
 100 1  one –
deci d  10−1 0.1  tenth 1795
centi c  10−2 0.01  hundredth 1795
milli m  10−3 0.001  thousandth 1795
micro μ  10−6 0.000001  millionth 1873
nano n  10−9 0.000000001  billionth  milliardth 1960
pico p  10−12 0.000000000001  trillionth  billionth 1960
femto f  10−15 0.000000000000001  quadrillionth  billiardth 1964
atto a  10−18 0.000000000000000001  quintillionth  trillionth 1964
zepto z  10−21 0.000000000000000000001  sextillionth  trilliardth 1991
yocto y  10−24  0.000000000000000000000001  septillionth  quadrillionth 1991
  1. Prefixes adopted before 1960 already existed before SI. 1873 was the introduction of the CGS system.

Symbol encoding in character sets

The official symbol for the SI prefix micro- is a Greek lowercase mu (μ).[4] For reasons stemming from its design, there are two different characters in Unicode, which appear slightly different in some fonts, although most fonts use the same glyph. The micro sign (µ) is encoded in the "Latin-1 Supplement" range identical to ISO/IEC 8859-1 (since 1987), at U+00B5 (Alt+0181),[5] residing at this code point also in DEC MCS (since 1983) and ECMA-94 (since 1985). The Greek letter (μ) is encoded in the Greek range at U+03BC (Alt+956). According to The Unicode Consortium, the Greek letter character is preferred,[6] but implementations must recognize the micro sign as well. This distinction also occurs in some legacy code pages, notably Windows-1253.

In circumstances in which only the Latin alphabet is available, ISO 2955 (1974,[7] 1983[8]), DIN 66030 (Vornorm 1973;[9] 1980,[10][11] 2002[12]) and BS 6430 (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. Similar, capacitor values according to the RKM code defined in IEC 60062 (IEC 62) (since 1952), EN 60062, DIN 40825 (1973), BS 1852 (1974), IS 8186 (1976) etc. can be written as 4u7 (or 4U7) instead of 4μ7 if the Greek letter μ is not available.

Other abbreviating conventions

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] or to write out "microgram" in full (see also List of abbreviations used in medical prescriptions). But 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 academia, "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]

gollark: ```Structured Markup Processing Tools html — HyperText Markup Language support html.parser — Simple HTML and XHTML parser html.entities — Definitions of HTML general entities XML Processing Modules xml.etree.ElementTree — The ElementTree XML API xml.dom — The Document Object Model API xml.dom.minidom — Minimal DOM implementation xml.dom.pulldom — Support for building partial DOM trees xml.sax — Support for SAX2 parsers xml.sax.handler — Base classes for SAX handlers xml.sax.saxutils — SAX Utilities xml.sax.xmlreader — Interface for XML parsers xml.parsers.expat — Fast XML parsing using Expat```... why.
gollark: There is no perfect language.
gollark: ```Internet Data Handling email — An email and MIME handling package json — JSON encoder and decoder mailcap — Mailcap file handling mailbox — Manipulate mailboxes in various formats mimetypes — Map filenames to MIME types base64 — Base16, Base32, Base64, Base85 Data Encodings binhex — Encode and decode binhex4 files binascii — Convert between binary and ASCII quopri — Encode and decode MIME quoted-printable data uu — Encode and decode uuencode files```Mostly should be libraries outside of the python core, and why are they not under file formats?
gollark: ```Concurrent Execution threading — Thread-based parallelism multiprocessing — Process-based parallelism The concurrent package concurrent.futures — Launching parallel tasks subprocess — Subprocess management sched — Event scheduler queue — A synchronized queue class _thread — Low-level threading API _dummy_thread — Drop-in replacement for the _thread module dummy_threading — Drop-in replacement for the threading module```Not THAT bad, since they mostly do different things.
gollark: Right beside each other.

See also

References
  1. 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 2017-08-14
  2. ISO 2955, table 2.
  3. Biology by Campbell & Reece, tenth edition. Ch. 6 "A Tour of the Cell". p. 98.
  4. Prefixes of the International System of Units, International Bureau of Weights and Measures (page visited on 9 May 2016).
  5. (Unicode 1.0, 1991)
  6. Unicode Technical Report #25
  7. ISO 2955-1974: lnformation processing - Representations of SI and other units for use in systems with limited character sets (1st ed.). 1974.
  8. "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.
  9. Vornorm DIN 66030 [Preliminary standard DIN 66030] (in German). January 1973.
  10. DIN 66030: Darstellungen von Einheitennamen in Systemen mit beschränktem Schriftzeichenvorrat (in German) (1st ed.). 1980.
  11. "Neue Normen für die Informationsverarbeitung". Computerwoche (in German). 1981-01-09. Archived from the original on 2016-12-14. Retrieved 2016-12-14.
  12. DIN 66030:2002-05 - Informationstechnik - Darstellung von Einheitennamen in Systemen mit beschränktem Schriftzeichenvorrat [Information technology - Representation of SI and other units in systems with limited character sets] (in German). Beuth Verlag. May 2002. Retrieved 2016-12-14.
  13. Burtis, Carl A.; Ashwood, Edward R.; Bruns, David E. (2012), Tietz Textbook of Clinical Chemistry and Molecular Diagnostics (5th ed.).
  14. "Commonly Used UCUM Codes for Healthcare Units". HL7 Deutschland e.V. Retrieved 2015-11-21.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.