Wikipedia:Naming conventions (technical restrictions)
Some page names are not possible because of limitations imposed by the MediaWiki software. In some cases (such as names which should begin with a lowercase letter, like eBay), a template can be added to the article to cause the title header to be displayed as desired. In other cases (such as names containing restricted characters) it is necessary to adopt and display a different title. This page describes appropriate ways to manage these situations.
Restrictions and workarounds
Restrictions on page titles are listed at Wikipedia:Page name § Technical restrictions and limitations. The most commonly encountered problems are that:
- titles cannot begin with a lowercase letter;
- titles cannot contain certain restricted characters.
There are two basic ways of handling a situation where the desired title of a page is technically impossible:
- Use the magic word DISPLAYTITLE to change the way the title header is displayed on the page (although the stored page name is not affected). This is often done through a template, the most common one being {{lowercase}}, which causes the title to be displayed with an initial lowercase letter, as in iPod.
- If this is not possible (due to restrictions on DISPLAYTITLE), choose a different title for the page, and use a template such as {{correct title}} to place a hatnote stating what the correct title should be. This is normally necessary in the case of restricted characters.
These templates should never be substituted (subst). To see which articles have these naming problems you can click on "What links here" in the toolbox for each template. If the template is substituted, it will no longer be linked.
Before declaring the current title to be "wrong" with the "correct title" template (or one of the more specific templates), please consider whether the title you are proposing as "correct" would really comply with Wikipedia conventions, particularly Wikipedia:Naming conventions (use English), Wikipedia:Manual of Style (capital letters) and Wikipedia:Manual of Style (trademarks).
Lowercase first letter
The MediaWiki software is configured so that a page title on the English Wikipedia (as stored in the database) cannot begin with a lower-case letter, and links that begin with a lower-case letter are treated as if capitalized, i.e. [[foo]]
is treated the same as [[Foo]]
.
Examples of articles affected by this problem are:
- eBay, located at EBay
- e (mathematical constant), located at E (mathematical constant)
- iOS, located at IOS (and various articles beginning with: iOS)
- man page, located at Man page
- pH, located at PH
- p:Machinery, located at P:Machinery
Examples of categories affected by this problem are:
- Category:macOS, located at Category:MacOS (and subcategories beginning with macOS)
Example of template affected by this problem:
- Template:iPhone models, located at Template:IPhone models
This also means that the page Long s, on the character ſ, cannot be moved to (or redirected from) ſ, as ſ is a lowercase letter whose uppercase form is S.
To fix this problem, you can place the {{lowercase title}}
wiki markup at the top of the article, category or template page (and optionally at the top of their talk/discussion page). This will cause the page title to be displayed with the initial letter in lowercase, as at eBay. Note that it does not fix every occurrence, like Wikipedia search bar search suggest drop-down list feature and Search results, as well as the page history, edit, log pages, or the browser address bar (it only affects the page title on the rendered HTML page and tab/window title bars).
Forbidden characters
Due to clashes with various elements of the MediaWiki software, some characters (and "characters") are not allowed to be part of page titles (nor are they supported by DISPLAYTITLE).
Clashes with wiki markup/HTML syntax
The following characters are forbidden due to clashes with wiki markup and HTML syntax:
# < > [ ] { } |
For articles about these characters, see number sign, less-than sign, greater-than sign, bracket (covers several characters), and vertical bar, respectively.
If the desired title of an article contains any of these characters, then an alternative title must be used instead. Often, you can simply remove the characters (e.g. MARRS instead of M|A|R|R|S). However, it may be necessary to spell out the character (e.g. C-sharp instead of C#) or use another substitute. Note that the sharp sign ♯ (different from the keyboard # character) can be used, as in C♯ (musical note).
In any of these cases, a hatnote should be placed at the top of the article informing readers what the correct title is. This is done using one of the following templates:
{{Correct title|Correct title|reason=#}}
for titles containing #{{Correct title|Correct title|reason=bracket}}
for titles containing < > [ ] { }{{Correct title|Correct title|reason=vbar}}
for titles containing |
Use {{!}} to represent the | character within the correct title.{{Correct title|Correct title}}
for cases not covered by any one of the above.
Examples:
- Song #3 is located at Song 3
- Point #1 is located at Point No. 1
- Look Out for #1 is located at Look Out for Number 1
- C# (programming language) is located at C Sharp (programming language)
- Cygnus OB2 #12 is located at Cygnus OB2-12
- [A→B] Life is located at (A→B) Life
- <|°_°|> is located at Robot Face
- While(1<2) is located at While(1 Is Less Than 2)
- [title of show] is located at title of show
- I am > I was is located at I Am Greater than I Was
Clashes with invalid-UTF-8 handling
Titles cannot contain invalid UTF-8 sequences (for our purposes, those that would decode to UTF-16 unpaired surrogates or code points beyond U+10FFFF). Thus, titles like %ED%9F%C0 (contains a UTF-8 sequence decoding to code point U+D800, an unpaired surrogate) or %F6%80%80%80 (contains a UTF-8 sequence decoding to code point U+180000, beyond the U+10FFFF limit) are invalid. (These examples use percent-encoded URLs rather than wikilinks, as the "characters" themselves should be impossible to insert into wikitext without percent-encoding.)
This also means that three valid UTF-8 sequences are forbidden in page titles (how these are displayed may vary depending on your browser and installed fonts):
� � �
The first of these characters or "characters", the replacement character, is forbidden because the MediaWiki software uses the replacement character to represent invalid UTF-8 sequences, and cannot differentiate this use as a placeholder from an actual instance of the replacement character. The other two (the two noncharacters at the end of Unicode plane 0, the Basic Multilingual Plane) are forbidden because the MediaWiki software uses the replacement character as a placeholder for these, just as it does for invalid UTF-8 sequences. Note, however, that the other 64 Unicode noncharacters (a block of 32 from U+FDD0 through U+FDEF, plus the two at the end of each of planes 1 through 16 [totaling another 32]) are not forbidden in page titles, as can be seen in the following examples:
Other problematic characters
Colons
In general, article titles containing colons are fine, subject to the following exceptions:
- Page names cannot begin with a colon. However, if the initial colon can be dropped to produce a satisfactory title, then this should be done, and the problem fixed with DISPLAYTITLE. (This will not work with more than one initial colon.) This happens because an initial colon is used for the colon trick.
- Article titles should not begin with a standard namespace prefix (Talk:, Help: etc.), as this will place them in the wrong namespace, which (among other problems) will exclude them from standard search results. In this case, another title must be found (it won't help to change the capitalization of the prefix or put spaces before or after the colon). For example, Help: A Day in the Life is located at Help!: A Day in the Life. A redirect is created at the original title (in this case at Help:A Day in the Life, which is what the above title resolves to).
- Article titles cannot begin with an interwiki or interlanguage prefix, or namespace alias. Again, these are case-insensitive, and putting spaces before or after the colon will not help. Examples:
- Lad: A Dog is located at Lad, A Dog (lad: is the prefix for Ladino Wikipedia)
- DK: King of Swing is located at DK King of Swing (dk: is one of the prefixes for the Danish Wikipedia, the other is da:)
- Portal: No Escape is located at Portal – No Escape (Portal: is a prefix for Wikipedia Portal Pages)
- Project: Mersh is located at Project Mersh (Project: is an alias for the Wikipedia namespace)
- V: The New Mythology Suite is located at V – The New Mythology Suite (v: is a prefix for Wikiversity)
- B: The Beginning is located at B – The Beginning (b: is a prefix for Wikibooks)
- C:Real is located at C Real (Greek band) (c: is a prefix for Wikimedia Commons)
- W:/2016Album/ is located at /2016Album/ but displays as having the correct title W:/2016Album/ (w: is a prefix for the English Wikipedia).
- In the case of aliases a redirect can be created. In the fourth example above this will be at Wikipedia:Mersh, which is what "Project: Mersh" resolves to.
Except in the case of initial colons and the w: and en: prefixes, DISPLAYTITLE will not work in the above situations. Use {{Correct title|Correct title|reason=:}}
.