PhysicsWiki:Manual of Style

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The Manual of Style (often abbreviated MoS or MOS) is a style guide for Physicswiki articles that encourages editors to follow consistent usage and formatting. This main page contains basic principles. Subpages with greater detail are linked in the menu to the right. If the Manual of Style does not specify a preferred usage, please discuss the issue on the talk page.


General principles

The Manual of Style is a guide applicable to all Physicswiki articles. It presents Physicswiki's house style, and is intended to help editors to produce articles with language, layout, and formatting that are consistent, clear, and precise. The goal is to make the whole encyclopedia easier and more intuitive to use.

Internal consistency

An overriding principle is that style and formatting choices should be consistent within a Physicswiki article, though not necessarily throughout Physicswiki as a whole. Consistency within an article promotes clarity and cohesion.

Stability of articles

The Arbitration Committee has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style, and that revert-warring over optional styles is unacceptable.[1] Where there is disagreement over which style to use in an article, defer to the style used by the first major contributor.

Follow the sources

Many points of usage, such as the treatment of proper names, can be decided by observing the style adopted by high-quality sources when considering a stylistic question. Unless there is a clear reason to do otherwise, follow the usage of reliable English-language secondary sources. If the sources can be shown to be unrepresentative of current English usage, follow current English usage instead—and consult more sources.


Writing should be clear and concise. Plain English works best: avoid jargon, and vague or unnecessarily complex wording.

Global view

Except in content with a local focus or where specific localized grammar or spelling is appropriate, or when an established precedent has been established and no clear reason has been accepted by a consensus to overturn it, content should be presented from a global view without bias towards any particular culture or group.

Article titles, headings, and sections

Article titles[R]

This is a summary of the policy governing the titles of Physicswiki's articles. It applies to the titles of Physicswiki articles, not of external articles that are cited. The guidance here also applies to Section headings, immediately below. Where these guidelines conflict, the balance between them should be decided by consensus.

  • Article titles should conform to Physicswiki's Article titles, including Use English.
  • Titles should match the article contents, and should be neither too narrow nor too broad.
  • The initial letter of a title is capitalized (except in rare cases, such as eBay). Otherwise, capital letters are used only where they would be used in a normal sentence (Funding of UNESCO projects, not Funding of UNESCO Projects).
  • To italicize a title, add the template {{italic title}} near the top of the article. Use of italics should conform to Physicswiki:ITALICS.
  • Do not use a, an, or the as the first word (Economy of the Second Empire, not The economy of the Second Empire), unless by convention it is an inseparable part of a name (The Hague).
  • Titles should be short.[2]
  • Titles should be nouns or noun phrases (nominal groups): Early life, not In early life.
  • Avoid special characters such as the slash (/), plus sign (+), braces ({ }), and square brackets ([ ]); use and instead of an ampersand (&), unless the ampersand is an accepted part of a name (Emerson, Lake & Palmer).
  • The final visible character of a title should not be a punctuation mark, unless the punctuation is part of a name (Saint-Louis-du-Ha! Ha!), an abbreviation is used (Inverness City F.C.), or a closing round bracket or quotation mark is required (John Palmer (schooner)).

Section headings

All of the guidance in Article titles immediately above applies to section headings as well, except for the use of {{italic title}}; section titles are italicized by the same double apostrophes as other text, but Physicswiki:ITALIC still applies. Headings provide an overview in the table of contents and allow readers to navigate through the text more easily.

  • Change a heading only after careful consideration, and if doing so use an anchor template to avoid breaking section links to it within the same article and from other articles.
  • Section and subsection headings should preferably be unique within a page; otherwise, after editing, the display can arrive at the wrong section (see also below) and the automatic edit summary can be ambiguous.
  • Headings should not normally contain links, especially where only part of a heading is linked.
  • Headings should not explicitly refer to the subject of the article, or to higher-level headings, unless doing so is shorter or clearer (Early life is preferable to His early life when his refers to the subject of the article; headings can be assumed to be about the subject unless otherwise indicated).
  • Spaced or unspaced multiple equal signs are the style markup for headings. The triple apostrophes (''') that make words appear in boldface are not used in headings. The nesting hierarchy for headings is as follows:
    • the automatically generated top-level heading of a page is H1, which gives the article title;
    • primary headings are then ==H2==, ===H3===, ====H4====, and so on until the lowest-level heading ======H6======.
  • Spaces between the == and the heading text are optional (==H2== is equivalent to == H2 ==). These extra spaces will not affect the way the heading is displayed to readers.
  • Include one blank line above the heading, for readability in the edit window. Some editors also prefer an (optional) blank line below the heading. (Only two or more blank lines above or below will add more white space in the public appearance of the page.)

Main article link

If the topic of a section is also covered in a dedicated article, show this by inserting {{main|Article name}} directly under the section heading.

Section management

  • When linking to a section of an article, leave an editor's note at that section, specifying the names of the linking articles so that if the title is altered, others can fix the links without having to perform exhaustive searches. For example:
==Evolutionary implications<!--This section is linked from [[Richard Dawkins]] and [[Daniel Dennett]]-->==
  • Consider a preemptive measure to minimize link corruption when the text of a heading changes: insert an {{anchor}} with the old name, which will then still work as an alternative link to that section. For example:
==New section name{{Anchor | Evolutionary implications}}<!-- This section is linked from [[Richard Dawkins]] and [[Daniel Dennett]] -->==
  • As explained in more detail at Physicswiki:Layout#Standard appendices and footers, optional appendix sections containing the following lists may appear after the body of the article in the following order: (a) books or other works created by the subject of the article; (b) internal links to related English Physicswiki articles; (c) notes and references; (d) recommended relevant books, articles, or other publications that have not been used as sources; and (e) recommended relevant websites that have not been used as sources and do not appear in the earlier appendices.

Capital letters

There are differences between the major varieties of English in the use of capitals (uppercase letters). Where this is an issue, the rules and conventions of the cultural and linguistic context apply. As with spelling, maintain consistency within an article.

Do not use capital letters for emphasis; where wording alone cannot provide the emphasis, use italics.

Incorrect: Contrary to popular belief, aardvarks are NOT the same as anteaters.
Correct: Contrary to popular belief, aardvarks are not the same as anteaters.

Use of "The" mid-sentence

Generally do not capitalize the definite article in the middle of a sentence. However, some idiomatic exceptions, including most titles of artistic works, should be quoted exactly according to common usage. Consider consulting the sources of the article.

Incorrect (generic): There was an article about The United Kingdom in yesterday's newspaper.
Correct (generic): There was an article about the United Kingdom in yesterday's newspaper.
Incorrect (title): J.R.R. Tolkien wrote the Lord of the Rings.
Correct (title): J.R.R. Tolkien wrote The Lord of the Rings.
Correct (title): Homer wrote the Odyssey.
Incorrect (exception): There are two seaside resorts in the Hague.
Correct (exception): There are two seaside resorts in The Hague.

Titles of people <span id="Titles"/>

  • When used generically, use lower case for words such as president, king, and emperor (De Gaulle was a French president; Louis XVI was a French king; Three prime ministers attended the conference).
  • When used as parts of a title, begin such words with a capital letter (President Obama, not president Obama). Standard or commonly used names of an office are treated as proper nouns (The British Prime Minister is David Cameron; Hirohito was Emperor of Japan; Louis XVI was King of France). Royal styles are capitalized (Her Majesty; His Highness); exceptions may apply for particular offices.
  • For the use of titles and honorifics in biographical articles, see Honorific prefixes.

Religions, deities, philosophies, doctrines, and their adherents

  • Religions, sects, and churches and their followers (in noun or adjective form) start with a capital letter. Generally, the is not capitalized before such names (the Shī‘a, not The Shī‘a). (However, see the style guide and naming convention for the Latter Day Saint movement.)
  • Religious texts (scriptures) are capitalized, but often not italicized (the Bhagavad Gita, the Qur’an, the Talmud, the Granth Sahib, the Bible). When the is used, it is not capitalized. Some derived adjectives are capitalized by convention, some are not (normally biblical but Koranic, for example); if unsure, check a dictionary appropriate to the topic, and be consistent within an article.
  • Honorifics for deities, including proper nouns and titles, start with a capital letter (God, Allah, the Lord, the Supreme Being, the Great Spirit, the Horned One, Bhagavan). Do not capitalize the unless it is formally a part of the name of the deity. The same is true when referring to major religious figures and figures from mythology by titles or terms of respect (the Prophet, the Messiah, the Virgin). Common nouns denoting deities or religious figures are not capitalized (the Romans worshipped many gods; many Anglo-Saxons worshipped the god Wotan; Jesus and Muhammad are both considered prophets in Islam; biblical scholars dispute whether Mary was a virgin for her entire life; her husband was her muse, but the nine Muses).
  • Pronouns and possessives referring to figures of veneration are not capitalized, even when they traditionally are in a religion's scriptures; they are left capitalized when directly quoting scriptures or any other texts that capitalize them.
  • Broad categories of mythical or legendary creatures do not start with uppercase capital letters (elf, fairy, nymph, unicorn, angel), although in derived works of fantasy, such as the novels of J.R.R. Tolkien and real-time strategy video games, initial capitals are sometimes used to indicate that the beings are regarded as forming a culture or a race in their fictional universes. Capitalize the names or titles of individual creatures (the Minotaur, the Pegasus) and of groups whose name and membership are fixed (the Magi or the Three Wise Men, the Cherubim). As with terms for deities, generalized references are not capitalized (the priests of this sect were called magi by some; several wise men were consulted; cherub-like).
  • Spiritual or religious events are likewise capitalized only when they are terms referring to specific incidents or periods (the Great Flood and the Exodus; but annual flooding and an exodus of refugees).
  • Philosophies, theories, movements, and doctrines do not begin with a capital letter unless the name derives from a proper noun (capitalism versus Marxism) or has become a proper noun (lowercase republican refers to a system of political thought; uppercase Republican refers to a political party or ideology. Use lower case for doctrinal topics or canonical religious ideas (as distinguished from specific events), even if they are capitalized by some religious adherents (virgin birth, original sin, transubstantiation).
  • Platonic or transcendent ideals are capitalized (Truth, the Good), but only within the context of philosophical doctrine; used more broadly, they are in lower case (Superman represents American ideals of truth and justice). Use capitals for personifications represented in art (The guidebook mentioned statues of Justice and Liberty).

Calendar items

  • Months, days of the week, and holidays start with a capital letter (June, Monday; the Fourth of July refers only to the US Independence Day—otherwise July 4 or 4 July).
  • Seasons are in lower case (her last summer; the winter solstice; spring fever), except in personifications or in proper names for periods or events (Old Man Winter; The team had great success on the Spring Circuit).

Animals, plants, and other organisms

When using scientific names, capitalize the genus but not the species (and italicize both); proper names incorporated into Latin species names are not capitalised. Common names shall not normally be capitalized (maple tree or zebra); as an exception to this general rule, the official common names of birds are capitalized (Bald Eagle). For new pages, ensure a redirect from the alternative capitalization to prevent article duplication.

Celestial bodies

  • When used generally, the words sun, earth, and moon do not take capitals (The sun was peeking over the mountain top; The tribal people of the Americas thought of the whole earth as their home), except for when the entities are personified (Sol Invictus ("Unconquered Sun") was the Roman sun god) or when the term refers to the names of specific astronomical bodies (The Moon orbits the Earth; but Io is a moon of Jupiter).
  • Names of planets, moons, asteroids, comets, stars, constellations, and galaxies are proper nouns, and therefore capitalized (The planet Mars can be seen tonight in the constellation Gemini, near the star Pollux; Halley's Comet is the most famous of the periodic comets; The Andromeda Galaxy is a spiral galaxy). The first letter of every word in such a name is capitalized (Alpha Centauri and not Alpha centauri; Milky Way, not Milky way).

Directions and regions

  • Do not capitalize directions such as north, except where they are parts of names. The same is true for their related forms (We took the northern road; but It was referred to by locals as the Great North Road). Composite directions may or may not be hyphenated, depending on the general style adopted in the article (Southeast Asia and northwest is more common in American English, and north-west in British English).
  • Do capitalize names of regions, including informal conventional names (Southern California; the Western Desert; Old Cow Hill); and similarly with persons referred to by place of origin or residence (He was the only Southerner among many Northerners). If uncertain whether to capitalize, do not.


  • Names of institutions (George Brown College) are proper nouns and require capitals. The word the at the start of a title is usually uncapitalized, but follow the institution's own usage (a degree from the University of Sydney; but researchers at The Ohio State University).
  • Generic words for institutions (university, college, hospital, high school) do not take capitals:
Incorrect (generic): The University offers programs in arts and sciences.
Correct (generic): The university offers programs in arts and sciences.
Correct (title): The University of Delhi offers programs in arts and sciences.
  • Political or geographical units such as cities, towns, and countries follow the same rules: the names of specific cities, towns, countries, and the like are proper nouns and require capitals; but generic words for types of government bodies do not take capitals. Sometimes, the full official name of a body is not needed.
Incorrect (generic): The City has a population of 55,000.
Correct (generic): The city has a population of 55,000.
Correct (title): The City of Smithville has a population of 55,000.
Correct (type unspecified): Smithville has a population of 55,000.


Write out both the full version and the abbreviation at first occurrence
When introducing a new name or term in an article, use the full name or term on its first occurrence, followed by the abbreviated form in round brackets. This clears the way for later use of the abbreviation alone (the New Democratic Party (NDP) won the 1990 Ontario election with a significant majority, at the first mention of the New Democratic Party; and the NDP quickly became unpopular with the voters, at a subsequent mention). An exception is made for abbreviations that are as well-known as or better known than their full names, such as "PhD" and "DNA", for which is it unnecessary to supply the full name on first occurrence.
Do not apply initial capitals in a full term that is a common noun just because capitals are used in the abbreviation.
Incorrect (not a name/proper noun): We used Digital Scanning (DS) technology
Correct: We used digital scanning (DS) technology
Correct: (name/proper noun): The film was produced by the British Broadcasting Corporation (BBC)
If the full term is already in round brackets, use a comma and or to indicate the abbreviation.
Correct They first debated the issue in 1992 (at a convention of the New Democratic Party, or NDP)
Plural and possessive forms
Acronyms and initialisms, like other nouns, become plurals by adding -s or -es (they produced three CD-ROMs in the first year; the laptops were produced with three different BIOSes in 2006). As with other nouns, no apostrophe is used unless the form is a possessive.
Periods (full stops) and spaces
The letters in an acronym or an initialism are generally not separated by full stops (periods) or blank spaces (GNP, NORAD, OBE, GmbH). Periods and spaces that were traditionally required have now dropped out of usage (PhD is now preferred over Ph.D. and Ph. D.). Full stops are not used in units of measurement; see Physicswiki:Manual of Style (dates and numbers) for more information.
Abbreviations formed by truncation (Hon. for Honorable), compression (cmte. for committee), or contraction (Dr. for Doctor) may or may not be closed with a period; a consistent style should be maintained within an article. A period is more usual in North American usage (Dr. Smith of 42 Drummond St.); no full stop is commonly preferred in British and other usage (Dr Smith of 42 Drummond St). British and some other authorities prefer to drop the stop from truncated and compressed abbreviations generally (XYZ Corp; ABC Ltd), a practice favored in science writing. Regardless of punctuation, any separate words in such abbreviations are spaced (op. cit. or op cit; not op.cit. or opcit).
US and U.S.
In American English, U.S. (with periods) is more common as the standard abbreviation for United States, although The Chicago Manual of Style now deprecates the use of the periods (16th ed.); US (without periods) is generally accepted in most other national forms of English. In longer abbreviations incorporating the country's initials (USN, USAF), periods are not used. When the United States is mentioned with one or more other countries in the same sentence, U.S. or US may be too informal, especially at the first mention (France and the United States, not France and the U.S.). For consistency in an article, if the abbreviated form for the United States appears alongside other abbreviated country names, avoid periods throughout; never add full stops to the other abbreviations (the US, the UK, and the PRC, not the U.S., the U.K., and the P.R.C.). Do not use the spaced U. S., nor the archaic U.S. of A., except when quoting. Do not use U.S.A. or USA, except in a quotation or as part of a proper name (Team USA).
Do not use unwarranted abbreviations
Avoid abbreviations when they might confuse the reader, interrupt the flow, or appear informal. For example, do not use approx. for approximate or approximately, except to reduce the width of an infobox or a table of data, or in a technical passage in which the term occurs many times.
See also Physicswiki:Manual of Style (dates and numbers) for when to abbreviate units of measurement.
Do not invent abbreviations or acronyms
Generally avoid making up new abbreviations, especially acronyms (World Union of Billiards is good as a translation of Union Mondiale de Billard, but neither it nor the reduction WUB is used by the organization; so use the original name and its official abbreviation, UMB). If it is necessary to abbreviate a heading in a wide table of data, use widely recognized initialisms (for United States gross national product use US and GNP, with a link if the term has not already been spelled out: US GNP; do not use the made-up initialism USGNP).
HTML elements
The software that Physicswiki runs on does not support the HTML phrase element <acronym> (see Mediazilla:671). The <abbr> element can be used instead: <abbr title="HyperText Markup Language">HTML</abbr> generates HTML.


Italics may be used sparingly to emphasize words in sentences (whereas boldface is normally not used for this purpose). Generally, the more highlighting in an article, the less its effectiveness.
Use italics when introducing terms, or distinguishing among them (The enamel organ is composed of the outer enamel epithelium, inner enamel epithelium, stellate reticulum, and stratum intermedium).
Use italics for the titles of works of literature and art, such as books, pamphlets, films (including short films), television series, music albums, and paintings. The titles of articles, chapters, songs, television episodes, and other short works are not italicized; they are enclosed in double quotation marks.
Italics are not used for major revered religious works (the Bible, the Qur'an, the Talmud).
<span id="Words as words" />Words as words
Use italics when mentioning a word or letter (see Use–mention distinction) or a string of words up to one full sentence (the term panning is derived from panorama, a word coined in 1787; the most commonly used letter in English is e). When a whole sentence is mentioned, quotation marks may be used instead, with consistency (The preposition in She sat on the chair is on; or The preposition in "She sat on the chair" is "on"). Mentioning (to discuss such features as grammar, wording, and punctuation) is different from quoting (in which something is usually expressed on behalf of a quoted source).
Foreign words
Use italics for phrases in other languages and for isolated foreign words that are not common in everyday English. Proper names (such as place names) in other languages, however, are not usually italicized.
<span id="Italics and quotations" />Quotations in italics
For quotations, use only quotation marks (for short quotations) or block quoting (for long ones), not italics. (See Quotations below.) This means that (1) a quotation is not italicized inside quotation marks or a block quote just because it is a quotation, and (2) italics are no substitute for proper quotation formatting. One way to distinguish long block quotes from ordinary text is to use {{quotation}}, which will box the text. Citation links may not work within such templates; if so, it may be necessary to use <blockquote> and </blockquote>.
Italics within quotations
Use italics within quotations if they are already in the source material. When adding italics on Physicswiki, add an editorial note [emphasis added] after the quotation.
"Now cracks a noble heart. Good night sweet prince: And flights of angels sing thee to thy rest" [emphasis added].
If the source has used italics (or some other styling) for emphasis and this is not otherwise evident, the editorial note [emphasis in original] should appear after the quotation.
Effect on nearby punctuation
Italicize only the elements of the sentence affected by the emphasis. Do not italicize surrounding punctuation.
Incorrect:    What are we to make of that?
Correct: What are we to make of that?
      (Note the difference between ? and ?. The question mark applies to the whole sentence, not just to the emphasized that.)
Correct: Four of Patrick White's most famous novels are A Fringe of Leaves, The Aunt's Story, Voss, and The Tree of Man.
(The commas, period, and the word and are not italicized.)
Italicized links
The italics markup must be outside the link markup, or the link will not work; however, internal italicization can be used in piped links.
Incorrect:    The opera [[''Turandot'']] is his best.
Correct: The opera ''[[Turandot]]'' is his best.
Correct: The [[USS Adder (SS-3)|USS ''Adder'' (SS-3)]] was a submarine.

Non-breaking spaces

A non-breaking space (also known as a hard space) is recommended to prevent the end-of-line displacement of elements that could be awkward at the beginning of a new line. Unlike normal spaces, multiple hard spaces are not compressed by browsers into a single space.

  • A hard space can be produced with the HTML code &nbsp; instead of the space bar: 19&nbsp;kg yields a non-breaking 19 kg.
  • A literal hard space, such as one of the Unicode non-breaking space characters, should not be used, since some web browsers will not load them properly when editing.
  • Hard spaces can also be produced by using the {{Nowrap}} template: {{Nowrap|8 sq ft}} produces a non-breaking 8 sq ft. This is especially useful for short constructions requiring two or more hard spaces, as in the preceding example. Template {{Nowrap}} has the disadvantage that if the enclosed text starts or ends with a space, these spaces are forced outside in the resulting HTML, and unpredicted breaks may occur. If &nbsp; occurs right before {{Nowrap}}, or at the start of text within {{Nowrap}}, some browsers allow a break at that point.
  • A non-breaking space should be used before a spaced en dash.
  • In some older browsers, quotation marks separated by a hard space are broken at the end of a line: "She said 'Yes!'&nbsp;" ("She said 'Yes!' "). Use "She said 'Yes!{{'"}} ("She said 'Yes!'") instead.


Minimal change

Preserve the original text, spelling, and punctuation. Where there is a good reason to make a change, insert an explanation within square brackets (for example, [her father] replacing him, where the context explaining him is omitted in the quotation). If there is a significant error in the original statement, use [sic], or the template {{sic}} (which produces [sic]), to show that the error was not made in transcription. Trivial spelling or typographical errors should be silently corrected (for example, correct ommission to omission, harasssment to harassment)—unless the slip is textually important.
Use ellipses to indicate omissions from quoted text. Legitimate omissions include extraneous, irrelevant, or parenthetical words, and unintelligible or guttural speech (umm, and hmm). Do not omit text where doing so would remove essential context or alter the meaning of the text. When quoting a vulgarity or obscenity, it should appear exactly as it does in the cited source; words should never be bowdlerized by replacing letters with dashes, asterisks, or other symbols. In carrying over such an alteration from a quoted source, [sic] may be used to indicate that the transcription is exact.

Allowable typographical changes

Although the requirement of minimal change is strict, a few purely typographical elements of quoted text should be conformed to English Physicswiki's conventions without comment. This practice of conforming typographical styling to a publication's own "house style" is universal. Allowable typographical alterations include these:
  • Styling of dashes and hyphens: see Dashes, below. Use the style chosen for the article: unspaced em dash or spaced en dash.
  • Styling of apostrophes and quotation marks: they should all be straight, not curly. See Quotation marks below. In quoting text from non-English sources, replace non-English typographical elements such as guillemets (« ») with their English-language equivalents; replace guillemets with straight quotation marks, and so on.
  • Spaces before punctuation such as periods and colons: these should be removed as alien to modern English-language publishing.
  • Some text styling should be altered. Of course the typeface will be automatically standardized; but generally preserve bold and italics (see Italics, above). Where the source is an old typewritten document such as an academic dissertation, underlining is almost certainly used to represent italics, and should be changed to italics as it would be by any book publisher.
  • When quoting from early modern sources, disused glyphs and ligatures should be normalized to modern usage when doing so will not change or obscure the meaning of the text. Examples of such changes include the following: æ→ae, œ→oe,ſ→s, and ye→the. Also, see Ampersand, below.
  • If an entire sentence is quoted in such a way that it becomes a grammatical part of the larger sentence, the first letter loses its capitalization (It turned out to be true that "a penny saved is a penny earned").

Quotations within quotations

When a quotation includes another quotation (and so on), start with double quote marks outermost, and, working inward, alternate single with double quote marks ("She disputed his statement that 'Voltaire never said "I disapprove of what you say, but I will defend to the death your right to say it."'", with three levels of quotation). Adjacent quote marks, as at the end of that last example, can be difficult to read ("'") unless kerned apart slightly with CSS; the {{" '}}, {{' "}} and {{" ' "}} templates will accomplish this; the example above is achieved by typing this: ... your right to say it.{{" ' "}}.


The author of a quote of a full sentence or more should be named; this is done in the main text and not in a footnote. However, attribution is unnecessary with quotations that are clearly from the person discussed in the article or section. When preceding a quotation with its attribution, avoid characterizing it in a biased manner.


As much as possible, avoid linking from within quotes, which may clutter the quotation, violate the principle of leaving quotations unchanged, and mislead or confuse the reader.

Block quotations

Format a long quote (more than four lines, or consisting of more than one paragraph, regardless of number of lines) as a block quotation, which Physicswiki's software will indent from both margins. Do not enclose block quotations in quotation marks (and especially avoid decorative quotation marks in normal use, such as those provided by the {{cquote}} template, which are reserved for pull quotes). Block quotations can be enclosed between a pair of <blockquote>...</blockquote> HTML tags; or use {{quotation}} or {{quote}}.

Physicswiki's Physicswiki software does not render multiple paragraphs inside a <blockquote> simply by spacing the paragraphs apart with blank lines. A workaround is to enclose each block-quoted paragraph in its own <p>...</p> element:

<p>And bring us a lot of horilka, but not of that fancy kind with raisins,
or with any other such things—bring us horilka of the purest kind, give us that
demon drink that makes us merry, playful and wild!</p>

<p>—[[Nikolai Gogol]], ''[[Taras Bulba]]''</p>

This will result in the following, indented on both sides (it may also be in a smaller font, depending on browser software):

And bring us a lot of horilka, but not of that fancy kind with raisins, or with any other such things—bring us horilka of the purest kind, give us that demon drink that makes us merry, playful and wild!

Nikolai Gogol, Taras Bulba

The {{quote}} template provides the same semantic HTML formatting, as well as a workaround for the paragraph spacing bug and a pre-formatted attribution line:

{{Quote|And bring us a lot of horilka, but not of that fancy kind with raisins,
or with any other such things—bring us horilka of the purest kind, give us that
demon drink that makes us merry, playful and wild!|[[Nikolai Gogol]]|''[[Taras Bulba]]''}}

This will result in:

And bring us a lot of horilka, but not of that fancy kind with raisins,

or with any other such things—bring us horilka of the purest kind, give us that

demon drink that makes us merry, playful and wild!

Foreign-language quotations

Quotations from foreign-language sources should be translated. Quotations which have been translated should be distinguished from those that have not. If they are available, the article should indicate the original source of the translation (if it was first published outside Physicswiki) and the original language (if it is not clear from the context).

If the original, untranslated text is available, editors are encouraged to provide a reference or to include it.



  • Consistent use of the straight (or typewriter) apostrophe ( ' ) is recommended, as opposed to the curly (or typographic) apostrophe (  ). For details and reasons, see Quotation marks, below.
  • To prevent apostrophes from being misinterpreted as Wiki markup, use the templates {{'}}, {{`}}, and {{'s}}, or use <nowiki> tags.
  • Foreign characters that resemble apostrophes, such as transliterated Arabic ayin ( ʿ ) and alif ( ʾ ), are represented by their correct Unicode characters (that is, U+02BF MODIFIER LETTER LEFT HALF RING and U+02BE MODIFIER LETTER RIGHT HALF RING respectively), despite possible display problems. If this is not feasible, use a straight apostrophe instead.
  • For usage of the possessive apostrophe, see the summary of usage issues at Possessives, below.
  • For a thorough treatment of all uses of the apostrophe (possessive, elision, formation of certain plurals, specific foreign-language issues) see the article Apostrophe.

Quotation marks[R]

The term quotation in the material below also includes other uses of quotation marks such as those for titles of songs, chapters, episodes, unattributable aphorisms, literal strings, "scare-quoted" passages, and constructed examples.

Double or single

Enclose quotations with double quotation marks (Bob said, "Jim ate the apple."). Enclose quotations within quotations with single quotation marks (Bob said, "Did Jim say 'I ate the apple' after he left?").

Physicswiki prefers double quotation marks because some search engines cannot find quotations within single quotation marks, like 'I ate the apple'. (Physicswiki's search facility will only find such an expression if the search string is also within single quotation marks.) In addition, double quotation marks are harder to confuse with apostrophes.

Article openings
When the title of an article appearing in the lead paragraph requires quotation marks (for example, the title of a song or poem), the quotation marks should not be in boldface, as they are not part of the title:
Correct: "Jabberwocky" is a nonsense poem by Lewis Carroll.
Block quotes
As already noted above, we use quotation marks or block quotes (not both) to distinguish long quotations from other text. Multiparagraph quotations are always block-quoted. The quotations must be precise and exactly as in the source (except for certain allowable typographical changes, also noted above). The source should be cited clearly and precisely to enable readers to locate the text in question, and to quote it accurately themselves from Physicswiki.
Quotation characters
Do not use grave and acute accents or backticks (`text´) as quotation marks (or as apostrophes).
There are two possible methods for rendering quotation marks at Physicswiki (that is, the glyphs, displayed with emphasis here, for clarity):
  • Typewriter or straight style: "text", 'text'. Recommended at Physicswiki.
  • Typographic or curly style: text, text. Not recommended at Physicswiki.
The exclusive use of straight quotation marks and apostrophes (see preceding section) is recommended. They are easier to type in reliably, and to edit. Mixed use interferes with some searches, such as those using the browser's search facility (a search for Alzheimer's disease could fail to find Alzheimer’s disease and vice versa).
Whenever quotation marks or apostrophes appear in article titles, make a redirect from the same title but using the alternative glyphs.

Punctuation inside or outside

On Physicswiki, place all punctuation marks inside the quotation marks if they are part of the quoted material and outside if they are not. This practice is sometimes referred to as logical punctuation. It is used here because it is deemed by Physicswiki consensus to be more in keeping with the principle of minimal change. This punctuation system does not require placing final periods and commas outside the quotation marks all the time but rather maintaining their original positions in (or absence from) the quoted material.

Correct: Arthur said, "The situation is deplorable and unacceptable."
(The period is known to be in the source.)
Correct: Arthur said that the situation was "deplorable".
(The period is either known not to be in the source, its presence in the source is uncertain, or its coverage within the quotation is considered unnecessary.)
Correct: Martha asked, "Are you coming?"
(The question mark belongs inside because the quoted text itself was a question.)
Correct: Did Martha say, "Come with me"?
(The very quote is being questioned, so the question mark belongs outside; any punctuation at the end of the original quote is omitted.)
When quoting a sentence fragment that ends in a period, some judgment is required: if the fragment communicates a complete sentence, the period can be placed inside. The period should be omitted if the quotation is in the middle of a sentence.
Correct: Martha said, "Come with me", and they did.
If the sequence of juxtaposed punctuation marks seems distracting or untidy, try an acceptable alternative.
Correct: Martha said, "Come with me" (and they did).

Brackets and parentheses

These rules apply to both round brackets ( ( ) ), often called parentheses, and square brackets ( [ ] ).

If a sentence contains a bracketed phrase, place the sentence punctuation outside the brackets (as shown here). However, where one or more sentences are wholly inside brackets, place their punctuation inside the brackets. (For examples, see Sentences and brackets, below.) There should be no space next to the inner side of a bracket. An opening bracket should be preceded by a space, except in unusual cases; for example, when it is preceded by an opening quotation mark, another opening bracket, or a portion of a word:

He rose to address the meeting: "(Ahem) ... Ladies and gentlemen, welcome!"
Only the royal characters in the play ([Prince] Hamlet and his family) habitually speak in blank verse.
We journeyed on the Inter[continental].

There should be a space after a closing bracket, except where a punctuation mark follows (though a spaced dash would still be spaced after a closing bracket), and in unusual cases similar to those listed for opening brackets.

If sets of brackets are nested, use different types for adjacent levels of nesting; for two levels, it is customary to have square brackets appear within round brackets. This is often a sign of excessively convoluted expression; it is often better to recast, linking the thoughts with commas, semicolons, colons, or dashes.

Avoid adjacent sets of brackets. Either put the parenthetic phrases in one set separated by commas, or rewrite the sentence:

Incorrect:    Nikifor Grigoriev (c. 1885–1919) (also known as Matviy Hryhoriyiv) was a Ukrainian insurgent leader.
Correct: Nikifor Grigoriev (c. 1885–1919), also known as Matviy Hryhoriyiv, was a Ukrainian insurgent leader.
Correct: Nikifor Grigoriev (c. 1885–1919) was a Ukrainian insurgent leader. He was also known as Matviy Hryhoriyiv.

Square brackets are used to indicate editorial replacements and insertions within quotations, though this should never alter the intended meaning. They serve three main purposes:

  • To clarify. (She attended [secondary] school, where this was the intended meaning, but the type of school was unstated in the original sentence.)
  • To reduce the size of a quotation. (X contains Y, and under certain circumstances, X may contain Z as well may be reduced to X contains Y [and sometimes Z].) When an ellipsis (...) is used to indicate that material is removed from a direct quotation, it should not normally be bracketed (see Ellipses, below).
  • To make the grammar work. (Referring to someone's statement "I hate to do laundry", one could properly write: She "hate[s] to do laundry".)

Sentences and brackets

  • If any sentence includes material that is enclosed in square or round brackets, it still must end—with a period, or a question or exclamation mark—after those brackets. This principle applies no matter what punctuation is used within the brackets:
She refused all requests (except for basics such as food, medicine, etc.).
  • However, if the entire sentence is within brackets, the closing punctuation falls within the brackets. (This sentence is an example.) This does not apply to matter that is added (or modified editorially) at the beginning of a sentence for clarity, which is usually in square brackets:
"[Principal Skinner] already told me that", he objected.
That is preferable to this, which is potentially ambiguous:
"He already told me that", he objected.
But even here consider an addition rather than a replacement of text:
"He [Principal Skinner] already told me that", he objected.
  • A sentence that occurs within brackets in the course of another sentence does not generally have its first word capitalized just because it starts a sentence. The enclosed sentence may have a question mark or exclamation mark added, but not a period. See the indented example above, and also:
Alexander then conquered (who would have believed it?) most of the known world.
Clare demanded that he drive (she knew he hated driving) to the supermarket.
It is often clearer to separate the thoughts into separate sentences or clauses:
Alexander then conquered most of the known world. Who would have believed it?
Clare demanded that he drive to the supermarket; she knew he hated driving.

Brackets and linking

If the text of a link needs to contain one or more square brackets, "escape" these using <nowiki>...</nowiki> tags or the appropriate numerical character reference.

He said "I spoke to [[John Doe|John &#91;Doe&#93;]] that morning."

He said "I spoke to John [Doe] that morning."

*Branwen, Gwern (2009). [ <nowiki>[WikiEN-l]</nowiki> Chinese start caring about copyright].

If a URL itself contains square brackets, the wiki-text should use the url-encoded forphysicswiki something.php?query=%5Bxxx%5Dxxx&whatever=else rather than query=[xxx]bar to avoid truncating the link text after "xxx". Of course, this issue only arises for external links as Physicswiki software forbids square brackets in page titles.


An ellipsis (plural ellipses) is an omission of material from quoted text; or some other omission, perhaps of the end of a sentence, often used in a printed record of conversation. The ellipsis is represented by ellipsis points: a set of three dots.

Ellipsis points, or ellipses, have traditionally been implemented in three ways:
  • Three unspaced periods (...). This is the easiest way, and gives a predictable appearance in HTML. Recommended.
  • Pre-composed ellipsis character (); generated with the &hellip; character entity, or as a literal "…". This is harder to input and edit, and too small in some fonts. Not recommended.
  • Three spaced periods (. . .). This is an older style that is unnecessarily wide and requires non-breaking spaces to keep it from breaking at the end of a line. Not recommended.
Function and implementation
Use an ellipsis if material is omitted in the course of a quotation, unless square brackets are used to gloss the quotation (see above, and points below).
  • Put a space on each side of an ellipsis, except that there should be no space between an ellipsis and:
    • a quotation mark directly following the ellipsis
    • any (round, square, curly, etc.) bracket, where the ellipsis is on the inside
    • sentence-final punctuation, or a colon, semicolon, or comma (all rare), directly following the ellipsis
  • Only place terminal punctuation after an ellipsis if it is textually important (as is often the case with exclamation marks and question marks, and rarely with periods).
  • Use non-breaking spaces (&nbsp;) only as needed to prevent improper line breaks, for example:
    • To keep a quotation mark from being separated from the start of the quotation ("...&nbsp;we are still worried").
    • To keep the ellipsis from wrapping to the next line ("France, Germany,&nbsp;... and Belgium but not the USSR").
Pause or suspension of speech
Three periods (loosely also called ellipsis points) are occasionally used to represent a pause in or suspense of speech, in which case the punctuation is retained in its original form (Virginia's startled reply was: "Could he ...? No, I cannot believe it!"). Avoid this usage on Physicswiki, except in direct quotations.
With square brackets
An ellipsis does not normally need square brackets around it, because its function is usually obvious—especially if the guidelines above are followed. Square brackets, however, may optionally be used for precision, to make it clear that the ellipsis is not itself quoted; this is usually only necessary if the quoted passage also uses three periods in it to indicate a pause or suspension. The ellipsis should follow exactly the principles given above, but with square brackets inserted immediately before and after it (Her long rant continued: "How do I feel? How do you think I ... look, this has gone far enough! [...] I want to go home!").


Commas are the most frequently used marks in punctuation. They can also be the most difficult to use well. Some important points are made in the Semicolons section below. Other points:

  • Pairs of commas are often used to delimit parenthetic material, forming a parenthetical remark. This interrupts the sentence less than a parenthetical remark in (round) brackets or dashes. Do not be fooled by other punctuation, which can mask the need for a comma, especially when it collides with a bracket or parenthesis, as in this example:
Incorrect: Burke and Wills, fed by local Aborigines (on beans, fish, and "ngardu") survived for a few months.
Correct:    Burke and Wills, fed by local Aborigines (on beans, fish, and "ngardu"), survived for a few months.
  • On Physicswiki, place quotation marks in accordance with the UK-based logical punctuation systephysicswiki
Incorrect: She said, "punctuation styles on Physicswiki change too often," as well as making other complaints.
Correct:    She said, "punctuation styles on Physicswiki change too often", as well as making other complaints.
  • Modern practice is against excessive use of commas; there are usually ways to simplify a sentence so that fewer are needed.
Awkward: Mozart was, along with the Haydns, both Joseph and Michael, and also Beethoven, one of Schubert's heroes.
Much better:    Schubert's heroes included Mozart, Beethoven, and Joseph and Michael Haydn.

Serial commas

A serial comma (also known as an Oxford comma or a Harvard comma) is a comma used immediately before a conjunction in a list of three or more items: the phrase ham, chips, and eggs includes a serial comma, while the variant ham, chips and eggs omits it. Editors may use either convention on Physicswiki so long as each article is consistent within itself. However, there are some times when the serial comma can create or remove confusion:

Sometimes omitting the comma can lead to an ambiguous sentence, as in this example: The author thanked her parents, Sinéad O'Connor and President Obama, which may list either four people (the two parents and the two people named) or two people (O'Connor and Obama, who are the parents).

Including the comma can also cause ambiguity, as in this example: The author thanked her mother, Sinéad O'Connor, and President Obama, which may list either two people (O'Connor, who is the mother, and Obama) or three people (the first being the mother, the second O'Connor, and the third Obama).

In such cases of ambiguity, there are three ways to clarify:

  • Use or omit the serial comma to avoid ambiguity.
  • Recast the sentence.
  • Format the list, such as with paragraph breaks and numbered paragraphs.

Recasting example one:

  • To list four people: The author thanked President Obama, Sinéad O'Connor, and her parents.
  • To list two people (the commas here set off non-restrictive appositives): The author thanked her father, President Obama, and her mother, Sinéad O'Connor.
    • Clearer (but more wordy): The author thanked her father and her mother, who are President Obama and Sinéad O'Connor respectively.

Recasting example two:

  • To list two people: The author thanked President Obama and her mother, Sinéad O'Connor.
  • To list three people: The author thanked her mother, President Obama, and Sinéad O'Connor.
    The clarity of the last example depends on the reader's knowing that Obama is male and cannot be a mother. If we change the example slightly, we are back to an ambiguous statement: The author thanked her mother, Irish President Mary McAleese, and Sinéad O'Connor.
    • Clearer: The author thanked President Obama, Sinéad O'Connor, and her mother; or The author thanked President Mary McAleese, Sinéad O'Connor, and her mother.


A colon (:) informs the reader that what comes after it demonstrates, explains, or modifies what has come before, or is a list of items that has just been introduced. The items in such a list may be separated by commas; or, if they are more complex and perhaps themselves contain commas, the items should be separated by semicolons:

We visited several tourist attractions: the Leaning Tower of Pisa, which I thought could fall at any moment; the Bridge of Sighs; the supposed birthplace of Petrarch, or at least the first known house in which he lived; and so many more.

A colon may also be used to introduce direct speech enclosed within quotation marks (see above).

In most cases a colon works best with a complete grammatical sentence before it. There are exceptions, such as when the colon introduces items set off in new lines like the very next colon here. Examples:

Correct: He attempted it in two years: 1941 and 1943.
Incorrect:    The years he attempted it included: 1941 and 1943.
Correct (special case):    Spanish, Portuguese, French: these, with a few others, are the West Romance languages.

Sometimes, more in American than British usage, the word following a colon is capitalized, if that word effectively begins a new grammatical sentence, and especially if the colon serves to introduce more than one sentence:

The argument is easily stated: We have been given only three tickets. There are four of us here: you, the twins, and me. The twins are inseparable. Therefore, you or I will have to stay home.

No sentence should contain more than one colon. There should never be a hyphen or a dash immediately following a colon. Only a single space follows a colon.


A semicolon (;) is sometimes an alternative to a full stop (period), enabling related material to be kept in the same sentence; it marks a more decisive division in a sentence than a comma. If the semicolon separates clauses, normally each clause must be independent (meaning that it could stand on its own as a sentence); often, only a comma or only a semicolon will be correct in a given sentence.

Correct: Though he had been here before, I did not recognize him.
Incorrect:    Though he had been here before; I did not recognize him.

Above, "Though he had been here before" cannot stand on its own as a sentence, and therefore is not an independent clause.

Correct: Oranges are an acid fruit; bananas are classified as alkaline.
Incorrect:    Oranges are an acid fruit, bananas are classified as alkaline.

This incorrect use of a comma between two independent clauses is known as a comma splice; however, in very rare cases, a comma may be used where a semicolon would seem to be called for:

Accepted: "Life is short, art is long." (citing a brief aphorism; see Ars longa, vita brevis)
Accepted: "I have studied it, you have not." (reporting brisk conversation, like this reply of Newton's)

A semicolon does not force a capital letter in the word that follows it.

A sentence may contain several semicolons, especially when the clauses are parallel; multiple unrelated semicolons are often signs that the sentence should be divided into shorter sentences, or otherwise refashioned.

Unwieldy: Oranges are an acid fruit; bananas are classified as alkaline; pears are close to neutral; these distinctions are rarely discussed.
One better way:    Oranges are an acid fruit, bananas are alkaline, and pears are close to neutral; these distinctions are rarely discussed.

Semicolon before "however"

The meaning of a sentence containing a trailing clause that starts with the word "however" depends on the punctuation preceding that word. A common error is to use the wrong punctuation, thereby changing the meaning to one not intended.

If used with the same meaning as "nevertheless", the word "however" should be preceded by a semicolon and followed by a comma. Example:

It was obvious they could not convert these people; however, they tried.
Meaning: It was obvious they could not convert these people. Nevertheless, they tried.

If the word "however" in the sentence means "in whatever manner", or "regardless of how", it may be preceded by a comma but not by a semicolon, and should not be followed by punctuation. Example:

It was obvious they could not convert these people, however they tried.
Meaning: It was obvious they could not convert these people, regardless of how they tried.

In the first case, the clause that starts with "however" cannot be swapped with the first clause; in the second case this can be done without change of meaning:

However they tried, it was obvious they could not convert these people.
Meaning: Regardless of how hard they tried, it was obvious they could not convert these people.

If the two clauses cannot be swapped, a semicolon is required.

A sentence or clause can also contain the word "however" in the middle if it was moved there from the front. In that case it can be changed to "though", and it is not the start of a clause; in this use the word may be enclosed between commas. Example:

He did not know, however, that the venue had been changed at the last minute.
Meaning: However, he did not know that the venue had been changed at the last minute.


Hyphens (-) indicate conjunction. There are three main uses.

  1. To distinguish between homographs (re-dress means dress again, but redress means remedy or set right).
  2. To link certain prefixes with their main word (non-linear, sub-section, super-achiever).
    • There is a clear trend to join both elements in all varieties of English (subsection, nonlinear), particularly in American English. British English tends to hyphenate when the letters brought into contact are the same (non-negotiable, sub-basement) or are vowels (pre-industrial), or where a word is uncommon (co-proposed, re-target) or may be misread (sub-era, not subera). American English reflects the same factors, but tends to close up without a hyphen when possible. Consult a good dictionary, and see Physicswiki:ENGVAR.
  3. To link related terms in compound modifiers:[3]
    • A hyphen can help with ease of reading (face-to-face discussion, hard-boiled egg); a hyphen is particularly useful in long noun phrases where non-experts are part of the readership, such as in Physicswiki's scientific articles: gas-phase reaction dynamics.
    • A hyphen can help to disambiguate (little-celebrated paintings is not a reference to little paintings; a government-monitoring program is a program that monitors the government, whereas a government monitoring program is a government program that monitors something else).
    • Many compounds that are hyphenated when used attributively (before the noun they qualify: a light-blue handbag), are not hyphenated when used predicatively (separated from the noun: the handbag was light blue). Hyphenation also occurs in proper names, such as Great Black-backed Gull. Where there would be a loss of clarity, the hyphen may be used in the predicative case as well (hand-fed turkeys, the turkeys were hand-fed).
    • A hyphen is not used after a standard -ly adverb (a newly available home, a wholly owned subsidiary) unless part of a larger compound (a slowly-but-surely strategy). A few words ending in -ly function as both adjectives and adverbs (a kindly-looking teacher; a kindly provided facility). Some such dual-purpose words (like early, only, northerly) are not standard -ly adverbs, since they are not formed by addition of -ly to an independent current-English adjective. These need careful treatment: Early flowering plants evolved along with sexual reproduction, but Early-flowering plants risk damage from winter frosts; northerly-situated islands.
    • A hyphen is normally used when the adverb well precedes a participle used attributively (a well-meaning gesture; but normally a very well managed firm, since well itself is modified); and even predicatively, if well is necessary to, or alters, the sense of the adjective rather than simply intensifying it (the gesture was well-meaning, the child was well-behaved, but the floor was well polished).
    • In some cases, like diode–transistor logic, the independent status of the linked elements requires an en dash instead of a hyphen. See En dashes below.
    • A hanging hyphen is used when two compound modifiers are separated (two- and three-digit numbers, a ten-car or -truck convoy, sloping right- or leftward, but better is sloping rightward or leftward).
    • Values and units used as compound modifiers are hyphenated only where the unit is given as a whole word; when the unit symbol is used, it is separated from the number by a non-breaking space (&nbsp;).
Incorrect: 9-mm gap
Correct: 9 mm gap (entered as 9&nbsp;mm gap)
Incorrect:    9 millimetre gap
Correct: 9-millimetre gap
Correct: 12-hour shift
Correct: 12 h shift

Multi-hyphenated items: It is often possible to avoid multi-word hyphenated modifiers by rewording (a four-CD soundtrack album may be easier to read as a soundtrack album of four CDs). This is particularly important where converted units are involved (the 6-hectare-limit (14.8-acre-limit) rule might be possible as the rule imposing a limit of 6 hectares (14.8 acres), and the ungainly 4.9-mile (7.9 km) -long tributary as simply 4.9-mile (7.9 km) tributary).

Spacing: A hyphen is never followed or preceded by a space, except when hanging (see above) or when used to display parts of words independently, such as the prefix sub- and the suffix -less.

Image filenames and redirects: A hyphen is used only to mark conjunction, not disjunction (for which en dashes are used: see below). An exception is in image filenames, where the ability to type the URL becomes more important (see the section on dashes below). Article titles with dashes should have a corresponding redirect from the title with hyphens: for example, Michelson-Morley experiment redirects to Michelson–Morley experiment, as the latter title, while correct, is harder to search for.

Hyphenation involves many subtleties that cannot be covered here; the rules and examples presented above illustrate the broad principles that inform current usage.


Two kinds of dashes are used on Physicswiki: en dashes and em dashes. Physicswiki:How to make dashes or the article on dashes shows common input methods for these punctuation marks.

Dashes should never be used in the filenames of images (use hyphens instead). Where used in an article or category's title, there should be a redirect from the version with a hyphen.

En dashes

En dashes (–, &ndash;) have several distinct roles.

  1. To stand for to or through in ranges (pp. 211–19, 64–75%, the 1939–45 war). Ranges expressed using prepositions (from 450 to 500 people or between 450 and 500 people) should not use dashes (not from 450–500 people or between 450–500 people). Number ranges must be spelled out if they involve a negative value or might be misconstrued as a subtraction (−10 to 10, not −10–10).
  2. To stand for to or versus (male–female ratio, 4–3 win, Lincoln–Douglas debate, France–Germany border).
  3. To stand for and between independent elements (diode–transistor logic, Michelson–Morley experiment). An en dash is not used for a hyphenated personal name (Lennard-Jones potential, named after John Lennard-Jones), nor a hyphenated place name (Guinea-Bissau), nor with an element that lacks lexical independence (the prefix Sino- in Sino-Japanese trade).
  4. To separate items in a list—for example, in articles about music albums, en dashes are used between track titles and durations, and between musicians and their instruments. In this role, en dashes are always spaced.
  5. In compounds whose elements themselves contain hyphens or spaces (the anti-conscription–pro-conscription debate) and when prefixing an element containing a space (pre–World War II technologies, ex–prime minister) – but usually not when prefixing an element containing a hyphen (non-government-owned corporations, semi-labor-intensive industries). However, recasting the phrase (the conscription debate, technologies prior to World War II) may be better style than compounding.
  6. As a stylistic alternative to em dashes (see below).

Disjunctive en dashes are unspaced, except when there is a space within either one or both of the items (the New York – Sydney flight; the New Zealand – South Africa grand final; June 3, 1888 – August 18, 1940, but June–August 1940). Exceptions are occasionally made where the item involves a spaced surname (Seifert–van Kampen theorem).

The space before an en dash should preferably be a non-breaking space (&nbsp;).

En dashes in article titles

When naming an article, do not use a hyphen as a substitute for an en dash that properly belongs in the title, for example in Eye–hand span. To aid searching and linking, provide a redirect from the corresponding article title with hyphens in place of en dashes, as in Eye-hand span.

Em dashes

Em dashes (—, &mdash;) indicate interruption in a sentence. They are used in two roles.

  1. Parenthetical (Physicswiki—one of the most popular web sites—has the information you need). A pair of em dashes for such interpolations is more arresting than a pair of commas, and less disruptive than round brackets.
  2. As a sharp break in the flow of a sentence—sharper than is provided by a colon or a semicolon.
  • In both roles, em dashes are useful where there are already several commas; em dashes can clarify the structure, sometimes removing ambiguity.
  • Use em dashes sparingly. They are visually striking, so two in a paragraph is often a good limit. Ensure there is no ambiguity if using multiple "sharp break" or parenthetical em dashes in the same area of the text.
  • Do not space em dashes.
Spaced en dashes as an alternative to em dashes
Spaced en dashes – such as here – can replace unspaced em dashes in all of the ways discussed above. Several major publishers use spaced en dashes to the complete exclusion of em dashes. Use one style consistently throughout an article.

Other dashes

Do not use substitutes for em or en dashes, such as the combination of two hyphens (--). These were typewriter approximations.


Generally avoid joining two words by a slash, also known as a forward slash or solidus ( / ). It suggests that the two are related, but does not specify how. It is often also unclear how the construct would be read aloud. Replace with clearer wording.

An example: The parent/instructor must be present at all times. Must both be present? (Then write the parent and the instructor.) Must at least one be present? (Then write the parent or the instructor.) Are they the same person? (Use a hyphen: the parent-instructor.)

In circumstances involving a distinction or disjunction, the en dash (see above) is usually preferable to the slash: the digital–analog distinction.

An unspaced slash may be used:

  • to indicate phonemic pronunciations (ribald is pronounced /ˈrɪbəld/)
  • to separate the numerator and denominator in a fraction (7/8 or 78)
  • to indicate regular defined yearly periods that do not coincide with calendar years (the 2009/10 academic year, the 2010/11 hockey season; see Physicswiki:Manual of Style (dates and numbers)#Longer periods)
  • where a slash occurs in a phrase widely used outside Physicswiki, and a different construction would be inaccurate, unfamiliar, or ambiguous

A spaced slash may be used:

  • to separate run-in lines when quoting poetry or song (To be or not to be: that is the question: / Whether 'tis nobler in the mind to suffer / The slings and arrows of outrageous fortune), or rarely when quoting prose, where careful marking of a paragraph break is textually important
  • to separate items that include at least one internal space (the NY 31 east / NY 370 exit), where for some reason use of a slash is unavoidable

Spaced slashes should be coded with a leading non-breaking space and a trailing normal space, as in x&nbsp;/ y (which renders as x / y), to prevent improper line breaks.

Do not use the backslash character ( \ ) in place of a slash.

Prefer the division operator ( ÷ ) to ( / ) when representing elementary arithmetic in general prose: 10 ÷ 2 = 5. In more advanced mathematical formulas, a vinculum or slash is preferred: or xn/n!. (See Physicswiki:Manual of Style (dates and numbers)#Common mathematical symbols and Help:Displaying a formula.)


Avoid the construct and/or on Physicswiki. In general, where it is important to mark an inclusive or, use x or y, or both, rather than x and/or y. For an exclusive or, use either x or y, and optionally add but not both, if it is necessary to stress the exclusivity.

Where more than two possibilities are presented, from which a combination is to be selected, it is even less desirable to use and/or. With two possibilities, at least the intention is clear; but with more than two it may not be. Instead of x, y, and/or z, use an appropriate alternative, such as one or more of x, y, and z; some or all of x, y, and z.

Sometimes or is ambiguous in another way: Wild dogs, or dingoes, inhabit this stretch of land. Are wild dogs and dingoes the same or different? For one case write: wild dogs (dingoes) inhabit ... (meaning dingoes are wild dogs); for the other case write: either wild dogs or dingoes inhabit ....

Number signs

  • Avoid using the # symbol (known as the number sign, hash sign, or pound sign) when referring to numbers or rankings. Instead use the word "number", or the abbreviation "No." For example:
Incorrect:    Her album reached #1 in the UK album charts.
Correct: Her album reached No. 1 in the UK album charts.
  • Do not use the symbol .

Terminal punctuation

  • Periods (also called "full stops"), question marks, and exclamation marks are terminal punctuation, the only punctuation marks used to end sentences in English.
  • In some contexts, no terminal punctuation is necessary. In such cases, the sentence often does not start with a capital letter. See Quotations, Quotation marks, and Sentences and brackets, above. Sentence fragments in captions or lists should in most cases not end with a period. See Formatting of captions and Bulleted and numbered lists below.
  • For the use of three periods in succession, see Ellipses, above.
  • Clusters of question marks, exclamation marks, or a combination of them (such as the interrobang), are highly informal and inappropriate in Physicswiki articles.
  • Use the exclamation mark with restraint. It is an expression of surprise or emotion that is generally unsuited to a scholarly or encyclopedic register.
  • Question marks and exclamation marks may sometimes be used in the middle of a sentence:
    • Why me? she wondered.
    • The Homeric question is not Did Homer write the Iliad? but How did the Iliad come into being?, as we have now come to realize.
    • The door flew open with a BANG! that made them jump. [Not encyclopedic, but acceptable in transcription from audio, or in direct quotation.]


In normal prose, never place a space before commas, semicolons, colons, or terminal punctuation, but place a space after them.

Spaces following terminal punctuation

The number of spaces following the terminal punctuation of a sentence in the wiki markup makes no difference on Physicswiki because the Physicswiki software condenses any number of spaces to just one when rendering the page (see Sentence spacing). For this reason, editors may use any spacing style they prefer on Physicswiki. Multiple spacing styles may coexist in the same article, and adding or removing a double space is sometimes used as a dummy edit.

Consecutive punctuation marks

Where a proper noun that includes terminal punctuation ends a sentence, do not add a second terminal punctuation mark. Where such a noun occurs mid-sentence, punctuation may be added.

Incorrect: Slovak returned to the Red Hot Chili Peppers in 1985 after growing tired of What Is This?.
Correct: Slovak returned to the Red Hot Chili Peppers in 1985 after growing tired of What Is This?
Correct: Slovak, growing tired of What Is This?, returned to the Red Hot Chili Peppers in 1985.

Punctuation and footnotes

Where footnotes (ref tags) are adjacent to most punctuation,[4] such as a comma or period, place them after the punctuation, with no intervening space:

The Sun's diameter is about 1,400,000 kilometres,<ref>Miller, E: ' 'The Sun' ', page 23. Academic Press, 2005.</ref> which dwarfs that of the Moon.<ref>Brown, R: "Size of the Moon", ' 'Scientific American' ', 51(78):46.</ref>

This will yield:

The Sun's diameter is about 1,400,000 kilometres,[1] which dwarfs that of the Moon.[2]

and in the Notes section below:

  1. ^ Miller, E: The Sun, page 23. Academic Press, 2005.
  2. ^ Brown, R: "Size of the Moon", Scientific American, 51(78):46.

Punctuation after formulae

A sentence that ends with a formula should have terminal punctuation (period, exclamation mark, or question mark) after the formula. Within a sentence, other punctuation (such as comma or colon) is used after a formula just as it would be if the text were not a formula. See Physicswiki:Manual of Style (mathematics)#Punctuation after formulae.

Geographical items

Places should generally be referred to consistently using the same name as in the title of their article (see Physicswiki:Naming conventions (geographic names)). Exceptions are made if there is a widely accepted historical English name appropriate to the given context. In cases where such a historical name is used, it should be followed by the modern name in round brackets (parentheses) on the first occurrence of the name in applicable sections of the article. This resembles linking; it should not be done to the detriment of style. On the other hand, it is probably better to provide such a variant too often than too rarely. If more than one historical name is applicable for a given context, the other names should be added after the modern English name, that is: "historical name (modern name, other historical names)".

Chronological items

Precise language

Avoid statements that will age quickly, except on pages concerning current events which are frequently brought up to date. Avoid recently, soon, and now (unless their meaning is fixed by the context). Avoid relative terms like currently (usually redundant), in modern times, is now considered, and is soon to be superseded. Instead, use either:

  • more precise and absolute expressions (since the start of 2005; during the 1990s; is expected to be superseded by 2008); or
  • an as of phrase (as of August 2007), which signals the time-dependence of the statement, and alerts later editors to update the statement (see As of); or simply use at instead: The population was over 21,000,000 (at December 2008).


Context determines whether the 12-hour clock or 24-hour clock is used; in both, colons separate hours, minutes, and seconds (1:38:09 pm and 13:38:09).

  • 12-hour clock times should end with dotted or undotted lower-case a.m. or p.m., or am or pm, which are spaced (2:30 p.m. or 2:30 pm, not 2:30p.m. or 2:30pm). A hard space (see above) is advisable: 2:30&nbsp;pm. Use noon and midnight rather than 12 pm and 12 am; whether midnight refers to the start or the end of a date will need to be specified unless this is clear from the context.
  • 24-hour clock times have no a.m., p.m., noon, or midnight suffix. 00:00 refers to midnight at the start of a date, 12:00 to noon, and 24:00 to midnight at the end of a date.


For which calendar to use, see Calendars.
  • Physicswiki does not add ordinal suffixes (such as -nd) or the, or put a comma between month and year.
Incorrect:    February 14th14th Februarythe 14th of February
Correct: 14 FebruaryFebruary 14
Incorrect: October, 1976October of 1976
Correct: October 1976
  • For guidance on which of the two standard formats to use (day before month or month before day), see Physicswiki:MOSNUM.
  • Dates are not normally linked.[5]
  • Date ranges are preferably given with minimal repetition, using an unspaced en dash where the range involves numerals alone (5–7 January 1979; January 5–7, 2002) or a spaced en dash where either opening or closing date has internal spaces (5 January – 18 February 1979; January 5 – February 18, 1979).
  • Rarely, a night may be expressed in terms of the two contiguous dates using a slash (the bombing raids of the night of 30/31 May 1942).
  • Yearless dates (5 March, March 5) are inappropriate unless the year is obvious from the context. There is no such ambiguity with recurring dates, such as January 1 is New Year's Day.
  • Dates in the format YYYY-MM-DD (like 1976-05-13) are uncommon in English prose and are generally not used in article prose. However, they may be useful in long lists, references, and tables for conciseness and ease of comparison.

Longer periods

  • Write months as whole words (February, not 2), except in the YYYY-MM-DD format (as in 2000-04-01). Use abbreviations such as Feb only where space is extremely limited, such as in tables and infoboxes. Do not insert of between a month and a year (April 2000, not April of 2000).
  • Seasons as dates. As the seasons are reversed in the northern and southern hemispheres—and areas near the equator tend to have just wet and dry seasons—neutral wording (in early 1990, in the second quarter of 2003, around September) is usually preferable to a "seasonal" reference (summer 1918, spring 1995). Even when the season reference is unambiguous (for instance when a particular location is clearly involved) a date or month may be preferable to a season name, unless there is a logical connection (the autumn harvest). Season names are preferable, however, when they refer to a phase of the natural yearly cycle (migration to higher latitudes typically starts in mid-spring).
  • Season names are not normally capitalized; for exceptions see Calendar items, above.
  • Years
    • Years are normally expressed in digits; a comma is not used in four-digit years (1988, not 1,988).
    • Avoid inserting the words the year before the digits (1995, not the year 1995), unless the meaning would otherwise be unclear.
    • Years are numbered according to the western calendar eras based on the traditionally reckoned year of the conception or birth of Jesus.
      • AD and BC are the traditional ways of referring to these eras. However, CE and BCE are becoming more common in academic and some religious writing. No preference is given to either style.
        • Do not use CE or AD unless the date would be ambiguous without it (The Norman Conquest took place in 1066; not 1066 CE or AD 1066).
        • BCE and CE or BC and AD are written in upper case, unspaced, without periods (full stops), and separated from the year number by a space or non-breaking space (5 BC, not 5BC).
        • Use either the BC–AD or the BCE–CE notation, but not both in the same article. AD may appear before or after a year (AD 106, 106 AD); the other abbreviations appear after (106 CE, 3700 BCE, 3700 BC).
      • Uncalibrated (bce) radiocarbon dates: 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 (such as ... 1360 bce [uncalibrated]), 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 BCEBC.
      • Year ranges, like all ranges, are separated by an en dash: do not use a hyphen or slash (2005–06 for a 24-month period, not 2005-06 or 2005/06). A closing CE–AD year is normally written with two digits (1881–86) unless it is in a different century from that of the opening year (1881–1986). The full closing year is acceptable, but abbreviating it to a single digit (1881–6) or three digits (1881–886) is not. A closing BCE–BC year is given in full (2590–2550 BCE). While one era signifier at the end of a date range still requires an unspaced en dash (12–5 BC), a spaced en dash is required when a signifier is used after the opening and closing years (5 BC – 29 AD).
      • A slash may be used to indicate regular defined yearly periods that do not coincide with calendar years (the financial year 1993/94).
      • Abbreviations indicating long periods of time ago—such as BP (Before Present), as well as various annum-based units such as ka (kiloannum) and kya (thousand years ago), Ma (megaannum), and Mya (million years ago), and Ga (gigaannum or billion years ago)—are given as full words and wikilinked on first occurrence.
      • To indicate around, approximately, or about, the abbreviations c. and ca. are preferred over circa, approximately, or approx., and are spaced (c. 1291). Use a question mark instead (1291?) only if the date is in fact questioned rather than approximate. (The question mark may mistakenly be understood as a sign that editors have simply not checked the date.)

  • Decades contain no apostrophe (the 1980s, not the 1980's); the two-digit form is used only where the century is clear (the '80s or the 80s).
  • Centuries and millennia are written using ordinal numbers, without superscripts and without Roman numerals: the second millennium, the 19th century, a 19th-century book (see also Numbers as figures or words below).


<span id="Spelling out numbers" />

Numbers as figures or words

  • Generally, for both ordinal numbers and cardinal numbers in the running text of an article:
    • Render single-digit whole numbers from zero to nine as words.
    • Render numbers greater than nine as figures or, with consistency within each article, render numbers over nine that take two words or fewer to say as words (about five million people; 16 or sixteen; 84 or eighty-four; 200 or two hundred; but 3.75, 544, 21 million). Words may be preferable for approximations.
  • Use figures in tables and infoboxes and in places where space is limited. Numbers within a table's explanatory text and comments should be consistent with the general rule above.
  • Show precise mathematical quantities, measurements, stock prices, etc., as figures.
  • Render comparable quantities, mentioned together, either all as words or all as figures (5 cats and 32 dogs, or five cats and thirty-two dogs; but not five cats and 32 dogs).
  • Render differently (with words or figures) adjacent quantities that are not comparable (thirty-six 6.4-inch rifled guns; not 36 6.4-inch rifled guns).
  • Render as words numbers that begin sentences. However, it is often better to recast the sentence so that it does not start with a number.
  • Do not use words for the numerical elements of dates and times, except where words are customary (Seventh of March Speech).
  • Show centuries in figures or words: (the 5th century BC; the 3rd century BCE; nineteenth-century painting).
  • Use words for simple fractions; but use the numerical fraction form in a percentage, with an abbreviated unit, or mixed with whole numbers (a quarter of a pound, but 14 lb; 1 14 slices). Use figures for decimal fractions (0.025).
  • Write proper names, idioms, and formal numerical designations in compliance with common usage, case by case (Chanel No. 5, 4 Main Street, 1-Naphthylamine, Channel 6). Do this even where it would cause a figure to open a sentence, although this can usually be avoided by rewording. Most proper names that include numbers use words (Fourth Amendment; Seventeenth Judicial District; Seven Years' War), but the proper names of military units usually do not (1st Indian Cavalry Division; 10th Air Base Wing).
  • Other specific exceptions are at Physicswiki:MOSNUM#Numbers as figures or words.

Large numbers

  • Use commas to break the sequence every three places: 2,900,000.
  • Because large rounded numbers are generally assumed to be approximations, about or similar qualifications are not normally needed.
  • Avoid over-precise values where they are unlikely to be stable or accurate, or where the precision is unnecessary in the context (The speed of light in a vacuum is 299,792,458 metres per second; but perhaps not The distance from the Earth to the Sun is 149,014,769 kilometres, since that distance varies; and not The population of Cape Town is 2,968,790, also variable, and unlikely to be accurate or useful).
  • In scientific contexts scientific notation is preferred (6.02 × 1023).
  • Where values in the millions occur a number of times through an article, upper-case M may be used for million, unspaced, and after using the full word at the first occurrence (She bequeathed her fortune of £100 million unequally: her daughter received £70M, her husband £18M, and her three sons just £4M each).
  • Billion is understood as 109. After the first occurrence in an article, billion may be abbreviated to unspaced bn ($35bn).

Decimal separator

  • Use a period character between the integral and the fractional parts of a decimal number, not a comma or a raised dot (6.57, not 6,57 or 6·57).
  • The number of decimal places should be consistent with others in the same context (The response rates were 41.0 and 47.4 percent, respectively; not The response rates were 41 and 47.4 percent, respectively), except for some rare cases in which the measurements were taken with unequal precision.
  • Use a leading zero for numbers between negative one and positive one (0.02, not .02), except in certain customary usages, such as sports performance averages and terms such as .22 caliber.


  • Generally, use either percent (American English) or per cent (British English) to indicate percentages in the body of an article.
  • The percentage symbol (%) is preferred in scientific or technical articles, in complex listings, and in articles where many percentages are reported.
  • Do not put a space before the symbol (71%, not 71 %).
  • In tables and infoboxes, use the percentage symbol, not the words (71%, not percent or per cent).
  • For ranges, use one percentage symbol, not two (22–28%, not 22%–28%).


  • In non-country-specific articles, express amounts of money in United States dollars, euros, or pounds sterling. Do not link the names or symbols of currencies that are commonly known to English-speakers ($, £, ), unless there is a particular reason to do so; do not use currency symbols which may be ambiguous, unless they are clear from the context of the article.
  • In country-specific articles, use the currency of the country. On first occurrence, consider including an approximate conversion to a major reserve currency such as U.S. dollars, euros, pounds: for example, Since 2001 the grant has been 10,000,000 Swedish kronor (approx. US$1.4M as at August 2009), alternatively: Since 2001 the grant has been 10,000,000 Swedish kronor (approx. €1.0M as at August 2009).
  • Generally, use the full name of a currency, and link it, on its first appearance if English-speakers are likely to be unfamiliar with it (52 Nepalese rupees); subsequent occurrences can use the currency sign (just 88 Rs).
  • Most currency signs are placed before the number; they are unspaced ($123), except for alphabetic signs (R 75).

Units of measurement

The 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: Physicswiki 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.

The articles that deal specifically with units of measurement, their names and their symbols address a number of situations including:

"The African elephant is 4 m at the shoulder"
"The African elephant is 4 m (13 ft) at the shoulder"
"The African elephant is 13 ft (4 m) at the shoulder" or
"The African elephant is 13 ft at the shoulder"

In instances where these principles appear to conflict with one another, consult other editors on the article's talk page and try to reach consensus.

Common mathematical symbols

  • For a negative sign or subtraction operator, use a minus sign (), Unicode character U+2212 MINUS SIGN. Input by clicking on it in the insert box beneath the edit window or by typing &minus;.
  • For a multiplication sign between numbers, use ×, which is input by clicking on it in the edit toolbox under the edit window or by typing &times;. However, the unspaced letter x is accepted as a substitute for by in such terms as 4x4.
  • Exponentiation is indicated using a superscript, an (typed as a<sup>n</sup>). Exponential notation can be spaced or unspaced, depending on circumstances.
  • Do not use programming language notation outside computer program listings. In most programming languages, subtraction, multiplication, and exponentiation are respectively represented by the hyphen-minus -, the asterisk *, and the caret or double asterisk ^ or **, and scientific notation is replaced by E notation.
  • Symbols for binary operators and relations are spaced on both sides:
    • plus, minus, and plus-or-minus (as binary operators): +, , ± (as in 5 − 3);
    • multiplication and division: ×, ÷;
    • equals, does not equal, equals approximately: =, , ;
    • is less than, is less than or equal to, is greater than, is greater than or equal to: <, , >, .
  • Symbols for unary operators are closed-up to their operand:
    • positive, negative, and positive-or-negative signs: +, , ± (as in −3);
    • other unary operators, such as the exclamation mark as a factorial sign (as in 5!).

Simple tabulation

Lines that start with blank spaces in the editing window are displayed boxed and in a fixed-width font, for simple tabulation. Lines that contain only a blank space insert a blank line into the table. For a complete guide to constructing tables, see Help:Table.



For the apostrophe character, see #Apostrophes above. For thorough treatment of the English possessive see Apostrophe.

  • For the possessive of most singular nouns, add 's (my daughter's achievement, my niece's wedding, Cortez's men, the boss's wife, Glass's books, Illinois's largest employer, Descartes's philosophy, Verreaux's eagle). Exception: abstract nouns ending with an /s/ sound, when followed by sake (for goodness' sake, for his conscience' sake).
  • For the possessive of singular nouns ending with just one s (sounded as /s/ or /z/), there are three practices:
    1. Add 's: James's house, Sam Hodges's son, Jan Hus's life, Vilnius's location, Brahms's music, Dickens's novels, Morris's works, the bus's old route.
    2. Add just an apostrophe: James' house, Sam Hodges' son, Jan Hus' life, Vilnius' location, Brahms' music, Dickens' novels, Morris' works, the bus' old route.
    3. Add either 's or just an apostrophe, according to how the possessive is pronounced:
      • Add only an apostrophe if the possessive is pronounced the same way as the non-possessive name: Sam Hodges' son, Moses' leadership;
      • Add 's if the possessive has an additional /ɪz/ at the end: Jan Hus's life, Morris's works.
      • Some possessives have two possible pronunciations: James's house or James' house, Brahms's music or Brahms' music, Vilnius's location or Vilnius' location, Dickens's novels or Dickens' novels.
  • Whichever of the above three options is chosen, it must be applied consistently within an article. When using the third option, if there is disagreement over the pronunciation of a possessive, the choice should be discussed and then that possessive adopted consistently in an article. (Possessives of certain classical and biblical names may have traditional pronunciations which may be deemed as taking precedence: Jesus' answer and Xerxes' expeditions, but Zeus's anger; and in some cases—particularly possessives of inanimate objects—rewording may be an option: the location of Vilnius, the old bus route, the moons of Mars.)
  • For a normal plural noun, ending with a pronounced s, form the possessive by adding just an apostrophe (my sons' wives, my nieces' weddings).
  • For a plural noun not ending with a pronounced s, add 's (women's careers, people's habits; The two Dumas's careers were controversial, but where rewording is an option, this may be better: The career of each Dumas was controversial).
  • Official names (of companies, organizations, or places) should not be altered (St Thomas' Hospital should therefore not be rendered as St Thomas's Hospital, even for consistency).
  • The possessive its (the dog chased its tail) has no apostrophe. (It's is the short form of it is or it has: it's a nice day, it's been a nice day.) Hers, ours, yours, theirs, and whose likewise lack apostrophes. Possessives of non-personal pronouns such as everyone, nobody, and anyone else are formed as if they were nouns (everyone's mother, nobody's hat, anyone else's opinion).

First-person pronouns

Physicswiki articles must not be based on one person's opinions or experiences, so the pronoun I is never used, except when it appears in a quotation. For similar reasons, avoid the pronoun we; a sentence such as We should note that some critics have argued in favor of the proposal sounds more personal than encyclopedic.

It is however acceptable to use we in figures of speech in which it is not meant as a literal reference to the author's personal viewpoint. For example:

  • In historical articles to mean the modern world as a whole: The text of De re publica has come down to us with substantial sections missing.
  • The author's we found in scientific writing. Albert Einstein wrote: "We are thus led also to a definition of "time" in physics." When one writes "Throughout the proof of this theorem we assume that the function ƒ is uniformly continuous.", it means that the proof is valid in cases in which that assumption is true. Often such things can be rephrased to avoid the first-person pronoun; for example, "Throughout the proof of this theorem it is assumed that the function ƒ is uniformly continuous."

Second-person pronouns

Use of the second person you, which is often ambiguous and contrary to the tone of an encyclopedia, is discouraged. Instead, refer to the subject of the sentence or use the passive voice, for example:

Do not use: When you move past "Go", you collect $200.
Use: When a player moves past "Go", that player collects $200.
Use: Players passing "Go" collect $200.

Gender-neutral language[R]

Use gender-neutral language where this can be done with clarity and precision. This does not apply to direct quotations or the titles of works (The Ascent of Man), which should not be altered; nor where all referents are of one gender, such as in an all-female school (When any student breaks that rule, she loses privileges).

Contested vocabulary

Avoid words and phrases that give the impression of straining for formality, that are unnecessarily regional, or that are not widely accepted. See List of English words with disputed usage and List of commonly misused English words; see also Identity below and Gender-neutral language above.


Uncontracted forms such as do not or it is are generally preferred to contracted ones such as don't or it's, as the latter are less formal. Contractions should not be expanded mechanically; they are sometimes acceptable, and when they aren't, they should often be removed by rewriting the sentence.

Instructional and presumptuous language

Avoid such phrases as remember that and note that, which address readers directly in an unencyclopedic tone. Similarly, phrases such as of course, naturally, obviously, clearly, and actually can make presumptions about readers' knowledge, and call into question the reason for including the information in the first place. We do not need to tell our readers that something is ironic, surprising, unexpected, amusing, coincidental, etc. Doing so inappropriately presents an editorial point of view. Simply state the sourced facts and allow readers to draw their own conclusions.

Subset terms

A subset term identifies a set of members of a larger class. Common subset terms are including, among, and et cetera (etc.). Do not use two subset terms (so avoid constructions like these: Among the most well-known members of the fraternity include ...; The elements in stars include hydrogen, helium and iron, etc.). Do not use including to introduce a complete list, where comprising, consisting of, or composed of would be correct.


The ampersand (&) represents the word and. In running prose, including dates that occur within running prose, and should be used instead. For example, "January 1 & 2" is not acceptable, but "January 1 and 2" is. Retain ampersands in titles of works or organizations, such as The Tom & Jerry Show or AT&T. Ampersands may be used with consistency and discretion in tables, infoboxes, and similar contexts where space is limited. Modern editions of old texts routinely replace ampersands with and (just as they replace other disused glyphs and ligatures), so an article's quotations may be cautiously modified, especially for consistency in quotations where different editions are used. (For similar allowable modifications see Quotations, above.)


Use the appropriate plural; allow for cases (such as oblast or octopus) in which a foreign word has been assimilated into English and normally takes an s or es plural, not its original plural.

Some collective nouns, such as army, company, crowd, fleet, government, majority, mess, number, pack and party, may refer either to a single entity or to the members that compose it. In British English, such words are commonly treated as singular or plural according to context. Names of towns and countries take plural verbs when they refer to sports teams but singular verbs when they refer to the actual place (or to the club as a business enterprise): in England are playing Germany tonight, the word England refers to a football team, but in England is the most populous country of the United Kingdom, it refers to the country. In North American English, these words (and the United States, for historical reasons) are almost invariably treated as singular. Also see Physicswiki:ENGVAR below.

National varieties of English

Subject to the guidelines below, the English Physicswiki does not prefer any major national variety of the language. No variant is inherently more correct than another. Cultural clashes over vocabulary, spelling, and grammar can be avoided by using the following four guidelines. (The accepted style of punctuation is covered in the punctuation section, above.) New users can be advised of this guideline using {{uw-lang}}.

Consistency within articles

Each article should consistently use the same conventions of spelling, grammar, and punctuation. For example, these should not be used in the same article: center and centre; organise and organize; color and colour; em dash and spaced en dash (see above). The exceptions are as follows:

  • quotations (retain the original variety of the quotation even if it differs from that of the article; though the precise styling of punctuation marks such as dashes, ellipses, apostrophes, and quotation marks should be made consistent with the surrounding article);
  • proper names (use the original spelling, for example United States Department of Defense and Australian Defence Force);
  • titles of media such as books or songs (again, use the original spelling; if there are multiple editions which spell a given title differently, use the one consulted); and
  • explicit comparisons of varieties of English.

Strong national ties to a topic

An article on a topic that has strong ties to a particular English-speaking nation should use the English of that nation. For example:

In a biographical or critical article, it may be best to use the subject's own variety of English (where there is a definite preference), especially if the author's writings are quoted in the article. For example, avoid American English commentary on quotations from Tolkien's very British prose. Quotes within the commentary should always use the variety of English used by the original source of the quote.

This guideline should not be used to claim national ownership of certain articles; see Physicswiki:OWN.

Retaining the existing variety

When an article has evolved sufficiently for it to be clear which variety of English it employs, the whole article should continue to conform to that variety, unless there are reasons for changing it based on strong national ties to the topic. When an article has not yet evolved to that point, the variety chosen by the first major contributor should be adopted. Where an article that is not a stub shows no signs of which variety it is written in, the first person to make an edit that disambiguates the variety is equivalent to the first major contributor.

An editor who determines the variety of English that is in use for a particular article may assist other editors by placing the appropriate Varieties of English template on the article's talk page to document that determination.

Opportunities for commonality

Physicswiki tries to find words that are common to all varieties of English.

  • Universally used terms are often preferable to less widely distributed terms, especially in article titles. For example, fixed-wing aircraft is preferred to the national varieties aeroplane (British English) and airplane (American English).
  • If one variant spelling appears in an article title, redirect pages are made to accommodate the other variants, as with Artefact and Artifact, so that all variants can be used in searches and in linking.
  • Terms that are uncommon in some varieties of English, or that have divergent meanings, may be glossed to prevent confusion. Insisting on a single term or a single usage as the only correct option does not serve the purposes of an international encyclopedia.
  • Use a commonly understood word or phrase in preference to one that has a different meaning because of national differences. For example, use alternative rather than alternate, since alternate may only refer to "alternating" to a speaker of British English.

Articles such as English plural and American and British English differences provide information on the differences between these major varieties of the language.


  • Disputes over how to refer to a person or group are addressed by policies such as Verifiability, Point of view, and Article titles where the term appears in the title of an article. When there is no dispute, the term most commonly used for a person will be the one that person uses for himself or herself, and the most common terms for a group will be those that the group most commonly uses for itself. Physicswiki should use them too. (See for example the article Jew, which demonstrates that most Jews prefer that term to "Jewish person".)
  • Any person whose gender might be questioned should be referred to using the gendered nouns, pronouns, and possessive adjectives that reflect that person's latest expressed gender self-identification. This applies when referring to any phase of that person's life. Nevertheless, avoid confusing or seemingly logically impossible text that could result from pronoun usage (for example: She fathered her first child).
  • Use specific terminology. For example, often it is more appropriate for people from Ethiopia (a country in Africa) to be described as Ethiopian, not carelessly (with the risk of stereotyping) as African.
  • The term Arab (never to be confused with Muslim or Islamic) refers to people and things of ethnic Arab origin. The term Arabic refers to the Arabic language or writing system, and related concepts (Not all Arab people write or converse in Arabic).
  • As always in a direct quotation, use the original text, even if the quoted text is inconsistent with the preceding guidelines.

Foreign terms

Foreign words should be used sparingly.

No common usage in English
Use italics for phrases in other languages and for isolated foreign words that are not current in English.
Common usage in English
Loanwords and borrowed phrases that have common usage in English—Gestapo, samurai, vice versa—do not require italics. A rule of thumb is not to italicize words that appear unitalicized in major English-language dictionaries.
Spelling and romanization

Names not originally in a Latin alphabet—such as Greek, Chinese, or Cyrillic scripts—must be romanized into characters generally intelligible to English-speakers. Do not use a systematically transliterated or otherwise romanized name if there is a common English form of the name, such as Tchaikovsky or Chiang Kai-shek.

The use of diacritics (accent marks) on foreign words is neither encouraged nor discouraged; their usage depends on whether they appear in verifiable reliable sources in English and on the constraints imposed by specialized Physicswiki guidelines. Place redirects at alternative titles, such as those without diacritics.

Spell a name consistently in the title and within the article (covered in Article titles), unless there is a good reason to use an alternative, such as may be given in Naming conventions (use English). For foreign names, phrases, and words generally, adopt the spellings most commonly used in English-language references for the article, unless those spellings are idiosyncratic or obsolete. If a foreign term does not appear in the article's references, adopt the spelling most commonly used in other verifiable reliable sources (for example other English-language dictionaries and encyclopedias). If a term appears rarely in English, an available alternative may be better.

Sometimes the usage will be influenced by other guidelines such as National varieties of English, above, which may lead to different choices in different articles.


  • Infoboxes, images and related content in the lead must be right-aligned.
  • Use captions to clarify the relevance of the image to the article (see Captions, below).
  • Images should be inside the major section containing the content to which they relate (within the section defined by the most recent level 2 heading)
  • Avoid sandwiching text between two images that face each other.
  • See this tutorial for how to group images, and avoid "stack-ups".
  • It is often preferable to place images of faces so that the face or eyes look toward the text. Multiple images in the same article can be staggered right-and-left (for example: Timpani). However, images should not be reversed simply to resolve a conflict between these guidelines; doing so misinforms the reader for the sake of our layout preferences. An image should be reversed or substantially altered only if this clearly assists the reader (for example, cropping a work of art to focus on a detail discussed in the text). Any such alteration must be noted in the caption.
  • The thumbnail option may be used ("thumb"), or another size may be fixed. The default thumbnail width is 220 pixels; users can adjust this in their preferences. An option such as "|300px|" resizes the image to the specified width in pixels, and "upright=1.2" (or "|frameless|upright=1.2" for plain pictures) resizes an image to approximately the given multiple of a user's preferred width. An image should generally be no more than 500 pixels tall and 400 pixels ("upright=1.8") wide, so it can be comfortably displayed next to the text on the smallest monitors in common use; an image can be wider if it uses the "center" or "none" options to stand alone. The {{Wide image}} and {{Tall image}} templates display images that would otherwise be unreasonably wide or tall. Examples where adjusting the size may be appropriate include, but are not limited to, the following:
    • Lead images, which should usually be no wider than "300px" ("upright=1.35").
    • Images in which detail is relatively unimportant (for example, a national flag), and which may need smaller sizes than usual.
    • Images containing important detail (for example, a map, diagram, or chart), and which may need larger sizes than usual.
    • Images in which a small region is relevant, but cropping to that region would reduce the coherence of the image.
  • Use {{Commons}} to link to more images on Commons, wherever possible. The use of galleries should be in keeping with Physicswiki's image use policy.
  • Alt text takes the place of an image for text-only readers, including those using screen readers. Images should have an alt attribute added to the |alt= parameter. See Physicswiki:ALT for more information.

Avoid entering textual information as images

Textual information should be entered as text rather than as an image, unless there is a good editorial reason for doing otherwise. True text may be colored and decorated with CSS tags and templates, but text in images cannot be. Images are not searchable, are slower to download, and are unlikely to be read as text by devices for the visually impaired. Even if some of these problems can be worked around, as by including a caption or alt text, editors should still consider whether an image of text really adds anything useful. Any important textual information in an image should also appear in the image's alt text, caption, or other nearby text.


Photographs and other graphics should always have captions, unless they are "self-captioning" (such as reproductions of album or book covers) or when they are unambiguous depictions of the subject of the article. For example, in a biography article, a caption is not mandatory for a portrait of the subject pictured alone, but might contain the name of the subject and additional information relevant to the image, such as the year or the subject's age.

Formatting of captions

  • Captions normally start with a capital letter.
  • Most captions are not complete sentences, but merely nominal groups (noun phrases, sentence fragments) that should not end with a period. If a complete sentence occurs in a caption, that sentence and any sentence fragments in that caption should end with a period.
  • Captions should not be formatted for boldness, size, color, etc. Exceptions for words that are conventionally italicized, occasionally apply.
  • Captions should be succinct; more information about the image can be included on its description page, or in the main text.

Bulleted and numbered lists

  • Do not use lists if a passage reads easily using plain paragraphs.
  • Do not leave blank lines between items in a bulleted or numbered list unless there is a reason to do so, since this causes the Wiki software to interpret each item as beginning a new list.
  • Use numbers rather than bullets only if:
    • a need to refer to the elements by number may arise;
    • the sequence of the items is critical; or
    • the numbering has some independent meaning, for example in a listing of musical tracks.
  • Use the same grammatical form for all elements in a list, and do not mix the use of sentences and sentence fragments as elements.
    • When the elements are complete sentences, they are formatted using sentence case and a final period.
    • When the elements are sentence fragments, they are typically introduced by a lead fragment ending with a colon. When these elements are titles of works, they retain the original capitalization of the title. Other elements are formatted consistently in either sentence case or lower case. Each element should end with a semicolon, with a period instead for the last element. Alternatively (especially when the elements are short), no final punctuation is used at all.



Make links only where they are relevant to the context: It is not useful and can be very distracting to mark all possible words as hyperlinks. Links should add to the user's experience; they should not detract from it by making the article harder to read. A high density of links can draw attention away from the high-value links that you would like your readers to follow up. Redundant links clutter the page and make future maintenance harder. (An example of a redundant link: the tallest people on Earth)

Check links: After linking, ensure that the destination is the intended one; many dictionary words lead to disambiguation pages and not to complete articles on a concept. An anchor into a targeted page—the label after an octothorpe (also called "hash sign": #) in a URL—will get readers to the relevant area within that page.

Initial capitalization: Physicswiki's Physicswiki software does not require that wikilinks begin with an upper-case character. Only capitalize the first letter where this is naturally called for, or when specifically referring to the linked article by its name: Snakes are often venomous, but lizards only rarely (see Poison).

External links

External links should not normally be used in the body of an article. Articles can include an external links section at the end to list links to websites outside Physicswiki that contain further information, as opposed to citing sources. The standard format is a primary heading named == External links == followed by a bulleted list of links. External links should identify the link and briefly indicate its relevance to the article subject. For example:

*[ History of NIH]
*[ National Institutes of Health homepage]

These will appear as:

Avoid listing an excessive number of external links; Physicswiki is not a link repository.


Keep markup simple

Use the simplest markup to display information in a useful and comprehensible way. Markup may appear differently in different browsers. Use HTML and CSS markup sparingly and only with good reason. Minimizing markup in entries allows easier editing.

In particular, do not use the CSS float or line-height properties because they break rendering on some browsers when large fonts are used.

Formatting issues

Alteration in the formatting of article prose such as font size, blank space, and color (about which, see #Color coding below) is an issue for the Physicswiki site-wide style sheet and should not be set except in special cases.

Typically, the use of custom font styles within the prose will:

  • reduce consistency, since the text will no longer look uniform;
  • reduce usability, since it might become impossible for people with custom stylesheets (for accessibility reasons, for example) to override it, and it might clash with a different skin as well as inconvenience people with color blindness; and
  • increase arguments, since other Physicswikins may disagree aesthetically with the choice of style.

Outside article prose, different font sizes are routinely used in navigation templates and infoboxes, tables (especially in larger ones), and some other contexts where other options are not available (such as table captions). Whenever specifying a font size, it should be done with a relative size, for example in CSS with font-size: 80% rather than an absolute size like font-size: 8pt.

Color coding

Do not use color alone to convey information (color coding). Such information is not accessible to people with color blindness, on black-and-white printouts, on older computer displays with fewer colors, on monochrome displays (PDAs, cell phones), and so on.

When conveying information via colors, choose colors that are unambiguous (such as maroon</font> and teal</font>) when viewed by a person with red-green color blindness (the most common type). Any information conveyed via shades of red and green should also be conveyed in some other way. Viewing the page with Vischeck can help determine whether the colors should be altered.

It is certainly desirable to use color as an aid for those who can see it, but the same information should still be accessible without it.

Technical language

While some topics are intrinsically technical, editors should take every opportunity to make them accessible to an audience wider than the specialists in the field, and to a general audience where possible. Jargon should be explained or avoided. {{Cleanup-jargon}} or {{Jargon-statement}} can be used to tag articles with jargon problems. An alternative for unavoidably technical articles is to write a separate introductory article (Introduction to special relativity). Avoid introducing too many new words for the purpose of "teaching the reader some new words" that are specialized to a field, when more common alternatives will do. Also, wikilinking as a mechanism for explanation (rather than a parenthetical in the article) is poor form, especially if done repeatedly.

Scrolling lists and collapsible content

Scrolling lists and boxes that toggle text display between hide and show should not be used to hide article content. This includes reference lists, image galleries, and image captions; they especially should not be used to conceal 'spoiler' information (see Physicswiki:Spoiler). Collapsible sections may be used in Navboxes or infoboxes, or in tables which consolidate information covered in the prose. When scrolling lists or collapsible content are used, care should be taken to ensure that the content will still be accessible on devices which do not support JavaScript and/or CSS.

Invisible comments

Editors use invisible comments to communicate with each other in the body of the text of an article. These comments are visible only in the wiki source (that is, in edit mode), not in read mode.

Invisible comments are useful for flagging an issue or leaving instructions about part of the text, where this is more convenient than raising the matter on the talk page. They should be used judiciously, because they can clutter the wiki source for other editors. Check that your invisible comment does not change the formatting, for example by introducing white space in read mode.

To leave an invisible comment, enclose the text you intend to be read only by editors between <!-- and -->. For example: <!--If you change this section title, please also change the links to it on the pages ...-->.


Pronunciation in Physicswiki is indicated using the International Phonetic Alphabet (IPA). In most situations, for ease of understanding by the majority of readers and across variants of the language, quite broad IPA transcriptions are best for English pronunciations. See Physicswiki:IPA for English and Physicswiki:IPA (general) for keys, and {{IPA}} for templates that link to these keys. For English pronunciations, pronunciation respellings may be used in addition to the IPA.

See also


  1. Physicswiki:Requests for arbitration/Jguk#Principles, Physicswiki:Requests for arbitration/jguk 2#Principles, and Physicswiki:Requests for arbitration/Sortan#Principles
  2. See Microcontent: Headlines and Subject Lines and First 2 Words: A Signal for the Scanning Eye.
  3. Specifically, compound attributives, which are modifiers of a noun that occur within the noun phrase.
  4. Dashes are an exception, as are some phrases within parentheses; see MOS:REFPUNC for full details on these exceptions.
  5. The use of autoformatting links for dates is now deprecated, per a poll. This refers to the system by which a date containing day, month and year can be surrounded by double square brackets to permit logged-in users to select a user preference for date formats.

Style guides on other Physicswiki projects

Further reading

Physicswikins are encouraged to familiarize themselves with other guides to style and usage, which may cover details that are not included in this Manual of Style. Among these are:

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