Wikipedia:Naming conventions (technical restrictions)

Some article titles cannot be named correctly due to limitations in the MediaWiki software. Currently known limitations are listed below in this article, though there may be others.

If this is the case, insert the following before the opening paragraph of the article:

{{wrongtitle|title=Correct Title}}

This will produce the text:

For a list of articles that are subject to these limitations, see Special:Whatlinkshere/Template:Wrongtitle.

Excluded characters

Characters not allowed at all in page titles

The following characters are not allowed in page titles:

# + < > [ ] | { }

and the character codes 0..31 and 127.

For example, the article on the C++ programming language is currently at C plus plus.

Attempting to use disallowed characters will result in a "bad title" error.

Forward slash

The forward slash (/) is allowed, but if it is the first character of the title normal links to it won't work as expected (they will prepend the title of the current page); a workaround is to use a html entity as the beginning of the link e.g. [[/test]].

(Slashes elsewhere in page titles can have some largely harmless side-effects, such as the spurious "< Talk:R" appearing in Talk:R/2004 S 1. See Wikipedia:Subpages.)

Question mark

Special attention should also be paid to the use of the question mark (?).

A page like Apple? or Orange can be created as usual by following the link. However, when typed into the address bar of a browser, everything following the question mark will be cut off. For example, typing in

http://en.wikipedia.org/wiki/Apple?_or_Orange

will direct you to apple. Instead, use

http://en.wikipedia.org/wiki/Apple%3F_or_Orange

This is a consequence of web server software treating everything after a ? as a query string. Whilst it would be possible to glue the url back together this would cause issues with urls like http://en.wikipedia.org/wiki/Apple?action=edit which is equivalent with http://en.wikipedia.org/w/index.php?title=Apple&action=edit

Spaces and underscores

Leading and trailing spaces and/or underscores (_) are stripped, multiple spaces and/or underscores are squashed together to a single underscore, and page names consisting of only spaces and/or underscores are not allowed at all.

Dot

Pages named . or .. and page names starting with ./ or ../ are not allowed at all.

Percent

MediaWiki supports percent-encoding in wiki links, in which a percent followed by two hexadecimal digits is converted to a single character. Thus, %25 is the same as %. Article titles containing a percent-encoded sequence are not allowed. For example, [[%2542]] should link to "%42", but doesn't link anywhere. A possible workaround would be to use non-ascii characters that look the same as the ones required; however this may create issues with older browsers.

If the two characters following the percent do not form a valid pair of hexadecimal digits, it works as expected.

Subscripts and superscripts

Currently, there is no way to directly include subscripts or superscripts in a page name.

Examples: NaKATPase, Lp space.

Attempting to workaround using Unicode subscripts and superscripts does not work on all browsers (depending also on the installed fonts and operating system), and only a small number of subscript and superscript characters exist on Unicode. Such an attempt was briefly made for minor planets, but was reverted after it became clear it was problematic. See also: Talk:2003 EL61#₆₁ characters ?, Talk:2003 UB313/Archive 1#Titling Policy Strawman, Wikipedia:Naming conventions (Unicode) (draft)#Superscripts and subscripts, Wikipedia talk:Naming conventions (Unicode) (draft)#Subs/Supers.

However, superscripts ¹, ², and ³ (which also exist on ISO 8859-1) do not have the same browser support limitations and can be used without problems, as long as a redirect from the title without the superscript is used.

Also at least one name (T_EX) is correctly written with a full size character lower than the normal ones. In page text this is achieved by combining sub and big but again this can't be done in article titles.

Configuration related limitations

The following limitations are not due to the MediaWiki software but to the settings of the English language Wikipedia. See the appropriate policy pages.

Lower case first letter

The English language encyclopedia is set not to accept a lower case character as the first letter of a page title.

Note: The template Template:Lowercase has been created as a proposed alternative to Template:Wrongtitle for this limitation, although it has not yet gained widespread use. The reason for its creation is discussed here.

Examples of large articles afflicted by this problem include:

eBay is located at EBay
pH is located at PH
five is located at Five (TV)
iTunes is located at ITunes
blink-182 is located at Blink-182
h2g2 is located at H2G2

This also means that the page Long s, on the character ſ, cannot be moved to ſ, as ſ is a lowercase letter whose uppercase form is S.

(Note: This is due to the present lack of infrastructure for case-insensitive title matching with sane case-preserving semantics in the MediaWiki software. The first letter of any link is forced to be upper case in order to allow links to work naturally both at the beginning of a sentence and in the middle. In the future, there may be a way added to make the initial letter appear lower case without breaking hundreds of thousands of links on the wiki or creating new avenues of abuse; however, there is currently no way to do this.)

A workaround for this issue is to insert a unicode word joiner at the start of the name. This can be done by entering ⁠ in the move page box. But like the workaround for percent this may cause browser support issues.

Colon

Article titles with a colon preceded by the title of a namespace are interpreted as being articles in that namespace so can't be used for articles in the main namespace. Article titles that would clash with an interwiki link prefix are also disallowed by the software (with a "bad title" error).

Examples of articles afflicted by this problem include:

Help: a Day in the Life is located at Help - a Day in the Life (Help: is a Wikipedia namespace)
Q: Are We Not Men? A: We Are Devo! is located at Are We Not Men We Are Devo! (Q: is a shortcut to Wikiquote)

Before adding a new namespace or interwiki prefix, care must be taken to move any existing articles out of the way. However this is a task for server admins (developers) not wiki sysops or normal users.

Browser support limitations

For now, use only precomposed characters. Avoid using combining diacritical marks. Use the text normalization NFC [1].