 | This guideline is a part of the English Wikipedia's Manual of Style. It is a generally accepted standard that editors should attempt to follow, though occasional exceptions may apply. Any substantive edit to this page should reflect consensus. When in doubt, discuss first on the talk page. |
| Manual of Style (MoS) |
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This part of the Manual of Style aims to achieve consistency in the use and formatting of dates and numbers in Wikipedia articles. Consistent standards make articles easier to read, write, and edit. Where this manual provides options, consistency should be maintained within an article, unless there is a good reason to do otherwise. In direct quotations, the original text should be preserved.
In June 2005, the Arbitration Committee stated that when either of two styles is acceptable, it is inappropriate for an editor to change an article from one to the other without substantial reason. For example, with respect to British date formats as opposed to American it would be acceptable to change from American format to British if the article concerned a British subject. Edit warring over optional styles (such as 14 February and February 14) is unacceptable. If an article has been stable in a given style, it should not be converted without a style-independent reason. Where in doubt, defer to the style used by the first major contributor.
Chronological items
editYear numbering systems
edit- Uncalibrated (bce) radiocarbon dates: Some source materials will indicate whether a date is calibrated or not simply by a change in capitalization; this is often a source of confusion for the unwary reader. Do not give uncalibrated radiocarbon dates (represented by the lower-case bce unit, occasionally bc or b.c. in some sources), except in directly quoted material, and even then include a footnote, a square-bracketed editor's note [like this], or other indication to the reader what the calibrated date is, or at least that the date is uncalibrated. Calibrated and uncalibrated dates can diverge surprisingly widely, and the average reader does not recognize the distinction between bce and BCE / BC.
- Abbreviations indicating long periods of time ago—such as BP (before present), as well as various annum-based units such as ka (kiloannum), Ma (megaannum) and Ga (gigaannum) are given as full words on first occurrence. Where source quotations use the abbreviations kya (thousand years ago), mya (million years ago), or bya (billion years ago) this should be explained to the reader, as in a measured Libby radiocarbon date of 35.1 mya [million years ago] had to be calibrated ... The kya, mya and bya symbols are deprecated in some fields such as geophysics and geology, but remain common in others, such as anthropology.
- BP: Do not convert other notations to BP unless you are certain of what you are doing. In some contexts the unit BP is actually defined as "years before January 1, 1950", not "years before the literal present", and the conversion may introduce an error if the date being converted is not a wide approximation (18,000 BP) but a more narrow one or an actual known year. BP years are given as 18,000 BP or spelled out as 18,000 years before present (not 18,000 YBP, 18,000 before present, 18,000 years before the present, or similar.)
Calendars
editDates can be given in any appropriate calendar, as long as the date in either the Julian or Gregorian calendars is provided, as described below. For example, an article on the early history of Islam may give dates in both Islamic and Julian calendars. Where a calendar other than the Julian or Gregorian is used, this must be clear to readers.
- Current events are given in the Gregorian calendar.
- Dates before the adoption of the Gregorian calendar on 15 October 1582 are normally given in the Julian calendar. The Julian day and month should not be converted to the Gregorian calendar, but the start of the Julian year should be assumed to be 1 January (see below for more details).
- Dates for Roman history before 45 BC are given in the Roman calendar, which was neither Julian nor Gregorian. When (rarely) the Julian equivalent is certain, it may be included.
- The Julian or Gregorian equivalent of dates in early Egyptian and Mesopotamian history is often debatable. Follow the consensus of reliable sources, or indicate their divergence.
- Dates of events in countries using the Gregorian calendar are given in the Gregorian calendar. This includes some of the Continent of Europe from 1582, the British Empire from 14 September 1752, and Russia from 14 February 1918 (see the Gregorian calendar article).
The dating method used in a Wikipedia article should follow that used by reliable secondary sources. If the reliable secondary sources disagree, choose the most common used by reliable secondary sources and note the usage in a footnote.
At some places and times, dates other than 1 January were used as the start of the year. The most common English-language convention was the Annunciation Style used in Britain and its colonies, in which the year started on 25 March, Annunciation Day; see the New Year article for a list of other styles. 1 January is assumed to be the opening date for years; if there is reason to use another start-date, this should be stated.
If there is a need to mention Old Style or New Style dates in an article (as in the Glorious Revolution), a footnote should be provided on the first usage, stating whether the New Style refers to a start of year adjustment or to the Gregorian calendar (it can mean either).
Time zones
editWhen writing a date, first consider where the event happened and use the time zone there. For example, the date of the Attack on Pearl Harbor should be December 7, 1941 (Hawaii time/date). If it is difficult to judge where, consider what is significant. For example, if a vandal based in Japan attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. If known, include the UTC date and time of the event in the article, indicating that it is UTC.
Numbers
editDelimiting (grouping of digits)
edit- Numbers with five or more digits to the left of the decimal point (i.e., 10,000 or more) should be delimited (visually separated into groups so they can be easily parsed) using commas every three digits; e.g., 12,200 and 255,200 and 8,274,527 etc.
- Numbers with four digits to the left of the decimal point may be delimited with a comma; that is, there were 1250 head of cattle and there were 1,250 head of cattle are both acceptable.
- Numbers are not delimited when they are part of mailing and shipping addresses, page numbers, and years with four or fewer digits; years with five or more digits use commas (e.g. 10,400 BC).
- In scientific articles, particularly those directed to an expert readership, numbers may be delimited with thin spaces using the {{gaps}} template. Coding
{{gaps|8|274|527}}produces 8274527 (note: the thin space character and its HTML entity, , do not render correctly on some browsers or on screen readers used by visually impaired people). - The style of delimiting numbers to the left of the decimal point must be consistent throughout an article.
- Constants in mathematics-oriented articles may be grouped in fives; e.g., 3.141592653589793238462643383279....
- Numbers with more than four digits to the right of the decimal point, particularly those in engineering and science where distinctions between different values are important, may be separated (delimited) into groups using the {{val}} template, which uses character-positioning techniques rather than distinct characters to form groups. According to ISO convention (observed by the NIST and the BIPM), it is customary to not leave a single digit at the end, so the last group comprises two, three, or four digits.
- The recommended progression on Wikipedia is as follows: 1.123, 1.1234, 1.12345, 1.123456, 1.1234567, 1.12345678, 1.123456789, etc. The {{val}} template handles these grouping details automatically; e.g.,
{{val|1.1234567}}generates 1.1234567 (with a four-digit group at the end); it can parse no more than a total of 15 significant digits in the significand. For significands longer than this, editors should delimit high-precision values using the {{gaps}} template; e.g.,{{gaps|1.234|567|890|123|456}}→ 1.234567890123456.
Fractions
editThe template {{frac}} is available for representing common fractions. For p⁄q, type {{frac|p|q}}. For N+p⁄q, type {{frac|N|p|q}}. When copied and pasted, N+p⁄q will appear as N+p/q.
Percentages
edit- Percent or per cent are commonly used to indicate percentages in the body of an article. The symbol % is more common in scientific or technical articles and in complex listings.
- The symbol is unspaced (71%, not 71 %).
- In tables and infoboxes, the symbol % is normally preferred to the spelled-out percent or per cent.
- Ranges are preferably formatted with one rather than two percentage signifiers (22–28%, not 22%–28%).
- Avoid ambiguity in expressing a change of rates. This can be done by using percentage points, not percentages, to express a change in a percentage or the difference between two percentages; for example, The agent raised the commission by five percentage points, from 10 to 15% (if the 10% commission had instead been raised by 5%, the new rate would have been 10.5%). It is often possible to recast the sentence to avoid the ambiguity (made the commission larger by half.). Percentage point should not be confused with basis point, which is a hundredth of a percentage point.
Natural numbers
edit(tag removed) mergeto|Manual of Style (mathematics)}} The set of natural numbers has two common meanings: {0, 1, 2, 3, ...}, which may also be called non-negative integers, and {1, 2, 3, ...}, which may also be called positive integers. Use the sense appropriate to the field to which the subject of the article belongs if the field has a preferred convention. If the sense is unclear, and if it is important whether or not zero is included, consider using one of the alternative phrases rather than natural numbers if the context permits.
Repeating decimals
editThe preferred way to indicate a repeating decimal is to place a bar over the digits that repeat. To achieve this the template {{overline}} can be used. For example, the markup 14.{{overline|285714}} gives 14.285714.
Consider a short explanation of the notation the first time this notation is used in an article. Some authors place the repeating digits in parentheses rather than using an overbar (perhaps because overbars are not available in their typesetting environment) but this should be avoided in Wikipedia to avoid confusion with expressing uncertainty.
Non-base-10 notations
editFor numbers expressed in bases other than base ten:
- In computer-related articles, use the C programming language prefixes 0x (zero-ex) for hexadecimal and 0 (zero) for octal. For binary, use 0b. Consider including a note at the top of the page about these prefixes.
- In all other articles, use subscript notation. For example: 1379, 2416, 2A912, A87D16 (use
<sub>and</sub>). - For base eleven and higher, use whatever symbols are conventional for that base. One quite common convention, especially for base 16, is to use upper-case A–F for digits from 10 through 15 (0x5AB3).
Scientific notation, engineering notation, and uncertainty
editNotations
edit- The template {{val}} can be used to facilitate the generation of scientific notation. It is a flexible tool that allows editors great latitude and must have arguments (each section between the vertical bars) properly entered in order for it to generate output that is compliant with formating conventions.
- Scientific notation is done in the format of one leading digit/decimal marker/rest of digits/×10n, where n is the integer that gives one leading digit.
- 1.602×10−19 is a proper use of scientific notation.
- 160.2×10−17 is not a proper use of scientific notation.
- Engineering notation is done in the format of leading digits/decimal marker/rest of digits/×10n, where n is a multiple of 3. The number of leading digits is adjusted accordingly.
- 132.23×106 is a proper use of engineering notation.
- 1.3223×108 is a not proper use of engineering notation.
- It is clearer to avoid mixing scientific notation and engineering notation in the same context (e.g., do not write A 2.23×102 m2 region covered by 234.0×106 grains of sand).
- Use discretion when it comes to using scientific and engineering notation. Not all values need to be written in it.
- Sometimes it is useful to compare values with the same power of 10 (often in tables) and scientific or engineering notation might not be appropriate.
Uncertainty
edit- Uncertainties can be written in various ways:
- Value/±/uncertainty/×/10n/unit symbol (e.g., (1.584±0.035)×1023 m)
- Do not group value and uncertainty in parenthesis before the multiplier (e.g., do not write (15.84 ± 0.35) × 1023 m)
- Value/superscript positive uncertainty/subscript negative uncertainty/×/10n/unit symbol (e.g., 15.84+0.43
−0.23×1023 m) - Value(uncertainty in the last digits)/×/10n/unit symbol (e.g., 1.584(35)×1023 m)
- Value/±/relative uncertainty(percent)/unit symbol (e.g., 15.84 ± 0.25% m)
- Value/±/uncertainty/×/10n/unit symbol (e.g., (1.584±0.035)×1023 m)
- The template {{val}} may be used to automatically handle all of this.
Units of measurement
editThe use of units of measurement is guided by the following principles:
- Avoid ambiguity: Aim to write so you cannot be misunderstood.
- Familiarity: The less readers have to look up definitions, the easier it is to be understood.
- International scope: Wikipedia is not country-specific; apart from some regional or historical topics, use the units in most widespread use worldwide for the type of measurement in question.
If there is trouble balancing these bullets, consult other editors through the talk page and try to reach consensus.
Which units to use and how to present them
editApply the following guidelines when choosing the "primary" unit for a measurement:
- Except in the cases mentioned below, put the units first that are in the most widespread use in the world. Usually, these are International System of Units (SI) units and non-SI units accepted for use with SI; but there are various exceptions for some measurements, such as years for long periods of time or the use of feet in describing the altitude of aircraft.
- With topics strongly associated with places, times or people, put the units most appropriate to them first. For example, in US articles, they usually are United States customary units, and for the UK, they usually are metric units for most measurements, but imperial units for some measurements such as road distances and draught beer (see, for example, Metrication in the United Kingdom and the Times Online style guide under "Metric").
- If editors cannot agree on the sequence of units, put the source value first and the converted value second. If the choice of units is arbitrary, use SI units as the main unit, with converted units in parentheses.
- Avoid inconsistent usage. Write a 600 metre (2000 ft) hill with a 650 metre (2,100 ft) hill, not a 2,000 foot (610 m) hill with a 650 metre (2,100 ft) hill.
- Nominal and defined values should be given in the original units first, even if this makes the article inconsistent: for example, When the Republic of Ireland adopted the metric system, the road speed limit in built-up areas was changed from 30 miles per hour (48 km/h) to 50 kilometres per hour (31 mph). (The focus is on the change of units, not on the 3.6% increase.)
- Avoid ambiguous unit names (e.g., write imperial gallon or US gallon rather than gallon). Only in the rarest of instances should ambiguous units be used, such as in direct quotations, to preserve the accuracy of the quotation.
- In scientific articles, use the units employed in the current scientific literature on that topic. This will usually be SI, but not always; for example, natural units are often used in relativistic and quantum physics, and Hubble's constant should be quoted in its most common unit of (km/s)/Mpc rather than its SI unit of s−1.
- Some disciplines use units not approved by the BIPM, or write them differently from BIPM-prescribed format. When a clear majority of the sources relevant to those disciplines use such units, articles should follow this (e.g., using cc in automotive articles and not cm3). Such non-standard units are always linked on first use.
- Use familiar units rather than obscure units—do not write over the heads of the readership (e.g., a general-interest topic such as black holes would be best served by having mass expressed in solar masses, but it might be appropriate to use Planck units in an article on the mathematics of black hole evaporation).
Unit conversions
edit- Generally, conversions to and from metric units and US or imperial units should be provided, except:
- When inserting a conversion would make a common expression awkward (The four-minute mile).
- When units are part of the subject of a topic—nautical miles in articles about the history of nautical law, SI units in scientific articles, yards in articles about American football—it can be excessive to provide conversions every time a unit occurs. It could be best to note that this topic will use the units (possibly giving the conversion factor to another familiar unit in a parenthetical note or a footnote), and link the first occurrence of each unit but not give a conversion every time it occurs.
- Converted values should use a level of precision similar to that of the source value, so the Moon is 380,000 kilometres (240,000 mi) from Earth, not (236,121 mi). However, small numbers may need to be converted to a greater level of precision where rounding would cause a significant distortion, so one mile (1.6 km), not one mile (2 km).
- Category:Conversion templates can be used to convert and format many common units, including {{convert}}, which includes non-breaking spaces.
- In a direct quotation, always keep the source units.
- Conversions required for units cited within direct quotations should appear within square brackets in the quote.
- Alternatively, you can annotate an obscure use of units (e.g. five million board feet of lumber) with a footnote that provides conversion in standard modern units, rather than changing the text of the quotation. See the style guide for citation, footnoting and citing sources.
- Measurements should be accompanied by a proper citation of the source using a method described at the style guide for citation.
- Where footnoting or citing sources for values and units, identify both the source and the original units.
Avoiding ambiguities
edit- Identify and define ambiguous units on their first use in an article.
- Avoid using unit abbreviations that have conflicting meanings in common units systems such as SI and US customary units:
- Use nmi (or NM) to abbreviate nautical mile rather than nm (nanometre).
- Use kn to abbreviate knot: kt could be confused with kilotonne; kN could be confused with kilonewton.
- Link such units to their definitions on first use.
- Some different units share the same name. These examples show the need to be specific.
- Use nautical mile or statute mile rather than mile in nautical and aeronautical contexts.
- Use long ton or short ton and not just ton; these units have no symbol or abbreviation and are always spelled out. The tonne, 1000 kilograms, is officially known as the metric ton in the US. Whichever name is used, the symbol is t.
- Use troy or avoirdupois ounce and not just ounce in articles about precious metals, black powder, and gemstones.
- Use fluid ounce explicitly to avoid confusion with weight, and specify, if it is Imperial, US or other fluid ounce.
- Use US gallon or imperial gallon rather than just gallon (also with quarts, pints, and fluid ounces).
- A calorie (symbol cal) refers to a gram calorie while the kilocalorie (symbol kcal) refers to the kilogram calorie (also known as small calorie and large calorie respectively). When used in a nutrition related article, use the kilocalorie as the primary unit. In US-related articles, use the synonym dietary calorie with a one-time link to kilogram calorie.
- For bits and bytes, specify whether the binary or decimal meaning of the prefixes kilo (k, K), mega (M), giga (G) and tera (T) is intended. See Quantities of bytes and bits.
- Avoid using unit abbreviations that have conflicting meanings in common units systems such as SI and US customary units:
- In tables and infoboxes, use unit symbols and abbreviations—do not spell them out.
- It may be appropriate to note that given quantities and conversions are approximate.
- When part of a full sentence, write approximately in full (e.g., write Earth's radius is approximately 6,400 kilometres, not Earth's radius is approx. 6,400 kilometres or Earth's radius is ~ 6,400 kilometres).
- In tables, infoboxes, or within brackets, use a tilde (~) or use approx. (e.g, write The capacity of a ship is sometimes expressed in gross register tons, a unit of volume defined as 100 cubic feet (~2.83 m3)).
- Do not note a conversion as approximate where the initial quantity has already been noted as such, (e.g., write Earth's radius is approximately 6,400 km (4,000 mi), not Earth's radius is approximately 6,400 km (approx. 4,000 mi).
Unit names and symbols
editConventions
edit- Where space is limited, such as in tables, infoboxes, and parenthetical notes, and in mathematical formulas, unit symbols are preferable. In prose it is usually better to spell out unit names, but symbols may also be used when a unit (especially one with a very long name) is used many times in an article. However, spell out the first instance of each unit in an article: for example The typical batch is 250 kilograms ... and then 15 kg of emulsifier is added.
- If a unit symbol which can be unfamiliar to a general audience is used in an article, it should be shown parenthetically after the first use of the full unit name: for example, His initial betatron reached energies of 2.3 megaelectronvolts (MeV), while subsequent betatrons achieved 300 MeV.
- Numerical ranges use unspaced en dashes if only one unit symbol is used at the end (e.g., 5.9–6.3 kg), and spaced en dashes if two symbols are used (e.g., 3000 nm – 1 mm); ranges in prose can be specified using either unit symbol or unit names, and units can be stated either after both numerical values or after the last (e.g., from 5.9 to 6.3 kilograms, from 5.9 kilograms to 6.3 kilograms, from 5.9 to 6.3 kg and from 5.9 kg to 6.3 kg are all acceptable).
- When dimensions are given, each number should be followed by a unit name or symbol (e.g., write 1 m × 3 m × 6 m, not 1 × 3 × 6 m or 1 × 3 × 6 m3).
Unit names
edit- Unit names, even those named after people, are common nouns. They are not capitalized when written in full, except where common nouns take a capital. Write The pascal is a unit of pressure, not The Pascal is a unit of pressure. In degree Celsius and degree Fahrenheit, the d is not usually capitalized, but the C and the F are. (The common noun is degree, Celsius being a proper adjective.)
- When unit names are combined by multiplication, separate them with a hyphen or space (e.g., newton-metre or newton metre). The plural is formed by pluralizing the last unit name (e.g., ten newton-metres).
- When unit names are combined by division, separate them with per (e.g., meter per second, not meter/second). The plural is formed by pluralizing the unit preceding the per, since it reads this many units of this per one unit of this (e.g., ten metres per second).
- When they form a compound adjective, values and unit names should be separated by a hyphen: for example, a five-day holiday.
Unit symbols
edit- Units symbols are preceded by figures, not by spelled-out numbers: for example, 5 min, not five min.
- Values and unit symbols are always separated by a non-breaking space. The {{nowrap}} template or the
character can be used for this purpose. For example, use 10 m or 29 kg, not 10m or 29kg.- Exceptions: Non-alphabetic symbols for degrees, minutes and seconds for angles and coordinates and the percent sign are unspaced (for example, 5° 24′ 21.12″ N for coordinates, 90° for an angle, 47% for a percentage, but 18 °C for a temperature). See also Manual of Style—Geographical Coordinates.
- Write unit symbols in upright roman type. (Italic type is normally reserved for variables and the like.) (e.g., 10 m or 29 kg, not 10 m or 29 kg).
- Standard symbols for units are undotted; e.g., m for the metre (not m.), kg for the kilogram (not kg.), in for the inch (not in., the quotation mark ", or the double prime ″), and ft for foot (not ft., the apostrophe ', or the prime ′).
- Non-standard abbreviations should be dotted.
- Symbols have no plural form—an s is never appended (e.g., kg, km, in, lb, not kgs, kms, ins, lbs. Write bit, not bits unless bits is used as a word rather than a symbol).
- When unit symbols are combined by multiplication, use a middle dot (
·) or a non-breaking space ( ) to separate the symbols. For example, ms is the symbol for the millisecond, while m·s or m s is the symbol for the metre-second. - When unit symbols are combined by division, use a slash to separate the symbols (e.g., for the metre per second use the symbol m/s, not mps) or use negative exponents (m·s−1). Exceptions include mph for the mile per hour, psi for pounds per square inch, etc.
- There should be no more than one slash per compound unit symbol (e.g., kg/(m·s), not kg/m/s or kg/m·s).
- Powers of unit symbols are expressed with a superscript exponent (write 5 km2, not 5 km^2).
- A superscript exponent indicates that the unit is raised to a power, not the unit and the quantity (3 metres squared is 9 square metres, or 9 m2).
- For areas and volumes, squared and cubed US customary or imperial length units may instead be rendered with sq and cu between the number and the unit symbol (e.g., 15 sq mi and 3 cu ft, not 15 mi sq and 3 ft cu).
- The symbols sq and cu are not used with BIPM-approved unit symbols.
- Avoid the Unicode characters ² and ³. They are harder to read on small displays, and are not aligned with superscript characters (e.g., x1x²x³x4 vs. x1x2x3x4). Instead, use superscript markup, created with <sup></sup>.
Units and symbols often written incorrectly
edit
- The degree symbol is ° (
°);. Using any other symbol (e.g., masculine ordinal º or ring above ˚) for this purpose is incorrect.
- The symbol for the bit is bit, not b. The byte may be represented by either one of the symbols B and byte, but not b or o (French: octet). Unless explicitly stated otherwise, one byte is eight bits (see History of byte).
- By extension, the symbols for the units of data rate kilobit per second, megabit per second and so on are kbit/s (not kbps or Kbps), Mbit/s (not Mbps or mbps), etc. Similarly, kilobyte per second and megabyte per second are kB/s (not kBps or KBps) and MB/s (not Mbps or MBps).
- The symbols for the degree Celsius, the degree Fahrenheit and the kelvin are °C (not C), °F (not F), and K (not °K). (C and F are the symbols for the coulomb and the farad; °K is the symbol for the degree Kelvin, the pre-1968 name of the kelvin.)
- For reasons of legibility, the preferred symbol for the unprefixed liter is upper-case L.
- If you need to express years as a unit, use the symbol a (Latin: annum) along with SI prefixes (e.g., write The half life of thorium-230 is 77 ka and The Cambrian is a geologic period that dates from 540 Ma to 490 Ma).
- There are many types of years (see year). When years are not used in the layman's meaning (e.g., Julie is 20 years old) clarify which type of year is meant.
- Roman prefixes are not used (M for 103, MM for 106, B for 109). Use SI prefixes instead.
Quantities of bytes and bits
edit
In quantities of bits and bytes, the prefixes kilo (abbreviated k or K), mega (M), giga (G), etc. are ambiguous. They may be based on a decimal system (like the standard SI prefixes), meaning 103, 106, 109, etc., or they may be based on a binary system, meaning 1024 (210), 10242, 10243, etc. The binary meanings are more commonly used in relation to solid-state memory (such as RAM), while the decimal meanings are more common for data transmission rates and disk storage.
Multiple-byte units
Decimal
Value
Metric
1000
kB
kilobyte
10002
MB
megabyte
10003
GB
gigabyte
10004
TB
terabyte
10005
PB
petabyte
10006
EB
exabyte
10007
ZB
zettabyte
10008
YB
yottabyte
10009
RB
ronnabyte
100010
QB
quettabyte
Binary
Value
IEC
Memory
1024
KiB
kibibyte
KB
kilobyte
10242
MiB
mebibyte
MB
megabyte
10243
GiB
gibibyte
GB
gigabyte
10244
TiB
tebibyte
TB
terabyte
10245
PiB
pebibyte
—
10246
EiB
exbibyte
—
10247
ZiB
zebibyte
—
10248
YiB
yobibyte
—
—
—
Orders of magnitude of data
The following recommendations are made for the use of these prefixes in Wikipedia articles:
- Editors should specify if the binary or decimal meanings of K, M, G, etc. are intended as the primary meaning. Consistency within each article is desirable, but the need for consistency may be balanced with other considerations.
- The definition most relevant to the article should be chosen as primary for that article (e.g., specify a binary definition in an article on RAM, decimal definition in an article on hard drives, and a binary definition for Windows file sizes, despite files usually being stored on hard drives).
- Where consistency is not possible, specify wherever there is a deviation from the primary definition.
- Disambiguation should be shown in bytes or bits, with clear indication of whether in binary or decimal base. There is no preference in the way to indicate the number of bytes and bits, but the notation style should be consistent within an article. Acceptable examples include:
- A 64 MB (64 × 10242 bytes) video card and a 100 GB (100 × 10003 bytes) hard drive
- A 64 MB (64 × 220 bytes) video card and a 100 GB (100×109 bytes) hard drive
- A 64 MB (67,108,864 bytes) video card and a 100 GB (100,000,000,000 bytes) hard drive
- Avoid inconsistent combinations such as A 64 MB (67,108,864 bytes) video card and a 100 GB (100 × 10003 bytes) hard drive. Footnotes, such as those seen in Power Macintosh 5500, may be used for disambiguation.
The IEC standard prefixes kibi-, mebi-, gibi-, etc. (symbols Ki, Mi, Gi, etc.) are not familiar to most Wikipedia readers, so are generally not to be used except under the following circumstances:
- when the article is on a topic where the majority of cited sources use the IEC prefixes,
- when directly quoting a source that uses the IEC prefixes,
- in articles specifically about or explicitly discussing the IEC prefixes.
Adopting suggestions from standards bodies
edit
Wikipedia's style guides do not necessarily conform to the prescriptions of standards bodies (e.g., BIPM and their SI, the IEC, and the ISO).
For instance, SI guidelines regarding the percent symbol (%) are often disregarded in practice. According to the BIPM's SI brochure (subsection 5.3.3), a space is always used to separate the unit symbol from the numeric value. Notable exceptions are the unit symbols for degree, minute, and second of plane angle (°, ′, and ″). However, according to the BIPM's SI brochure (subsection 5.3.7), the exception does not apply to the percent symbol, stating: "When [the percent symbol] is used, a space separates the number and the symbol %." This practice has not been well adopted with regard to the % symbol, and per current Wikipedia consensus, is contrary to Wikipedia's Manual of Style. Use 50%, not 50 %.
Wikipedia follows common practice regarding bytes and other data traditionally quantified using binary prefixes (e.g., mega- and kilo-, meaning 220 and 210 respectively) and their unit symbols (e.g., MB and KB). Despite the IEC's 1998 guideline creating several new binary prefixes (e.g., mebi-, kibi-) to distinguish the meaning of the decimal SI prefixes (e.g., mega- and kilo-, meaning 106 and 103 respectively) from the binary ones, consensus on Wikipedia currently favours the retention of the binary prefixes in computing-related contexts. Use 256 MB of RAM, not 256 MiB of RAM.
Currencies
edit
Common mathematical symbols
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- See also: Manual of Style (mathematics).
- For a negative sign or subtraction operator, use a minus sign (−). You can input a minus sign by either keying in − or by clicking on it in the insert box beneath the edit window (located between the ± and × signs). Do not use an en dash (–), do not use a hyphen (-) unless writing code, and do not use an em dash (—).
- For a multiplication sign, use ×, which can be input by clicking on it in the edit toolbox under the edit window or by keying in × (however, the letter x is accepted as a substitute for by in such terms as 4x4).
Common mathematical symbols
Name
Operation
Other use
Symbol
Wikicode
ASCII
Unicode
As binary operator
(e.g., 1 + 1)
As unary operator
(e.g., +1)
Plus sign
Addition
Positive sign
+
+
+
U+002B
Spaced
Unspaced
Plus or minus
Addition or subtraction
Positive or negative sign
±
±
±
U+00B1
Spaced
Unspaced
Minus or plus
Subtraction or addition
Negative or positive sign
∓
—
∓
U+2213
Spaced
Unspaced
Minus sign
Subtraction
Negative sign
−
−
−
U+2212
Spaced
Unspaced
Multiplication sign, cross
Multiplication, vector product
—
×
×
×
U+00D7
Spaced
—
Division sign, obelus
Division
—
÷
÷
÷
U+00F7
Spaced
—
Equal sign
Equation
—
=
—
=
U+003D
Spaced
—
Not equal sign
Non-equation
—
≠
≠
≠
U+2260
Spaced
—
Approximate sign
Approximation
—
≈
≈
≈
U+2248
Spaced
—
Less than sign
Inequation
—
<
<
<
U+3C
Spaced
—
Less than or equal to
Inequation
—
≤
≤
≤
U+2264
Spaced
—
Greater than sign
Inequation
—
>
>
>
U+3E
Spaced
—
Greater than or equal to
Inequation
—
≥
≥
≥
U+2265
Spaced
—
Unnecessary vagueness
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Use accurate measurements whenever possible.
Vague
Precise
The wallaby is small
The average male wallaby is 1.6 metres (63 in) from head to tail.
Prochlorococcus marinus is a tiny cyanobacterium.
The cyanobacterium Prochlorococcus marinus is 0.5 to 0.8 micrometre across.
The large oil spill stretched a long way down the Alaskan coast.
The oil spill that drifted down the Alaskan coast was 3 statute miles (5 km) long and 1,000 feet (300 m) wide.
A beautiful little house in Malibu
A $400,000 residential property in Malibu
Geographical coordinates
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- For draft guidance on, and examples of, coordinates for linear features, see Wikipedia:WikiProject Geographical coordinates/Linear.
- Quick guide:
To add 57°18′22″N 4°27′32″W / 57.30611°N 4.45889°W to the top of an article, use {{Coord}}, thus:
{{Coord|57|18|22|N|4|27|32|W|display=title}}
These coordinates are in degrees, minutes, and seconds of arc.
"title" means that the coordinates will be displayed next to the article's title at the top of the page (in desktop view only; title coordinates do not display in mobile view) and before any other text or images. It also records the coordinates as the primary location of the page's subject in Wikipedia's geosearch API.
To add 44°06′45″N 87°54′47″W / 44.1124°N 87.9130°W to the top of an article, use either
{{Coord|44.1124|N|87.9130|W|display=title}}
(which does not require minutes or seconds but does require the user to specify north/ south and east/west) or
{{Coord|44.1124|-87.9130|display=title}}
(in which the north and east are presumed by positive values while the south and west are negative ones).
These coordinates are in decimal degrees.
- Degrees, minutes and seconds, when used, must each be separated by a pipe ("|").
- Map datum must be WGS84 if possible (except for off-Earth bodies).
- Avoid excessive precision (0.0001° is <11 m, 1″ is <31 m).
- Maintain consistency of decimal places or minutes/seconds between latitude and longitude.
- Latitude (N/S) must appear before longitude (E/W).
Optional coordinate parameters follow the longitude and are separated by an underscore ("_"):
- dim:
dim:N (viewing diameter in metres)
- region:
region:R (ISO 3166-1 alpha-2 or ISO 3166-2 code)
- type:
type:T (landmark or city(30,000), for example)
Other optional parameters are separated by a pipe ("|"):
- display
|display=inline (the default) to display in the body of the article only,|display=title to display at the top of the article only (in desktop view only; title coordinates do not display in mobile view), or|display=inline,title to display in both places.
- name
name=X to label the place on maps (default is PAGENAME)
Thus: {{Coord|44.1172|-87.9135|dim:30_region:US-WI_type:event
|display=inline,title|name=accident site}}
Use |display=title (or |display=inline,title) once per article, for the subject of the article, where appropriate.
- Per WP:ORDER, the template is placed at the bottom of the article in the 'end matter', after any navigation templates, but before all categories, including the {{DEFAULTSORT}} template. This template may also be placed within an infobox, instead of at the bottom of the article.
- For full details, refer to {{Coord/doc}}.
- Additional guidance is available at obtaining coordinates and converting coordinates.
Geographical coordinates on Earth should be entered using a template to standardize the format and to provide a link to maps of the coordinates. As long as the templates are adhered to, a robot performs the functions automatically.
First, obtain the coordinates. Avoid excessive precision.
Two types of template are available:
- {{coord}}, which has replaced the coor family (and combined their functionality), offers users a choice of display format through user styles, emits a Geo microformat, and is supported by Google Earth.
- Infoboxes such as {{Infobox settlement}}
Depending on the form of the coordinates, the following formats are available.
For just degrees (including decimal values):
{{coord|dd|N/S|dd|E/W}}
For degrees/minutes:
{{coord|dd|mm|N/S|dd|mm|E/W}}
For degrees/minutes/seconds:
{{coord|dd|mm|ss|N/S|dd|mm|ss|E/W}}
where:
- DD, MM, SS are the degrees, minutes, seconds, listed in sequence
- N/S is either N or S, depending on which hemisphere, and
- E/W is either E or W, depending on which hemisphere
- negative values may be used in lieu of S and W
For example:
The city of Oslo, located at 59° 55′ N, 10° 44′ E, enter:
{{coord|59|55|N|10|44|E}} — which becomes 59°55′N 10°44′E / 59.917°N 10.733°E
A country, like Botswana, less precision is appropriate:
{{coord|22|S|24|E}} — which becomes 22°S 24°E / 22°S 24°E
Higher levels of precision are obtained by using seconds
{{coord|33|56|24|N|118|24|00|W}} — which becomes 33°56′24″N 118°24′00″W / 33.94000°N 118.40000°W
Coordinates can be entered as decimal values
{{coord|33.94|S|118.40|W}} — which becomes 33°56′S 118°24′W / 33.94°S 118.40°W
Increasing or decreasing the number of decimal places can control the precision. Trailing zeroes should be included.
London Heathrow Airport, Amsterdam, Jan Mayen and Mount Baker are examples of articles that contain geographical coordinates.
Generally, the larger the object being mapped, the less precise the coordinates should be. For example, if just giving the location of a city, precision greater than 100 meters is not needed unless specifying a particular point in the city, for example the central administrative building. Specific buildings or other objects of similar size would justify precisions down to 10 meters or even one meter in some cases (1′′ ~15 m to 30 m, 0.0001° ~5.6 m to 10 m).
The final field, following the E/W, is available for specification of attributes, such as type, region and scale.
When you have added the coordinates, you might want to remove the {{coord missing}} tag from the article, if present.
For more information, see the geographical coordinates WikiProject.
Templates other than {{coord}} should use the following variables for coordinates: lat_d, lat_m, lat_s, lat_NS, long_d, long_m, long_s, long_EW.
See also
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- For page naming specifics, see Wikipedia:Naming conventions (numbers and dates).
- m:Help:Date formatting feature at Meta
- Displaying numbers and numeric expressions
Notes
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