References

References or footnotes can be used within an article to cite sources, provide tangential information and commentary, or provide other explanatory information. They rely on the Cite extension and will automatically generate a list of footnotes at the bottom of the article.

Overview

A reference is generated with HTML tags (see below) or by selecting the Insert Reference in the Visual Editor. Any text placed between these two tags or input in the Visual Editor field will then display at the bottom of the article or wherever <references/> is placed in the article. It's generally recommended to place the reference table at the bottom of the article, under a specific heading.

Once placed, the reference will create a superscript link enclosed in square brackets that will automatically scroll the page to the reference and highlight it when clicked:

References are dynamically generated and automatically numbered by the software according to the order they appear in the article.

Usage

Formatting

There are no set rules when it comes to formatting a reference and each wiki can create their own standard formatting. Formatting can vary greatly between wikis and can be anything: A link to another article on the wiki that contains the source (see here), a direct quotation (see here), or a block of text.

It's generally a good idea to avoid placing images in references, as these will rarely display correctly, causing other references to become unreadable.

Code

Cite extension is the software extension for the footnotes system. Two HTML-style tags are used to define and show the references.

<ref>

Single use footnotes are defined by enclosing content within <ref>...</ref>:

<ref>content</ref>

A footnote used multiple times may be defined with a name:

<ref name="foo">content</ref>

To invoke a named footnote:

<ref name="foo" />

Footnotes may be defined in groups:

<ref group="foo">content</ref>

Names and groups may not be a numeric integer. The quotes are optional unless the name includes a space, punctuation or other mark. It is recommended that names be kept simple and restricted to the ASCII character set.

<references />

To display the reference list, after all of the <ref>...</ref> tags, include:

<references />

To display footnotes defined in a group include:

<references group="foo" />

Error messages

The Cite extension has the ability to detect errors. This section documents the error messages and provides an understanding of the problem and solutions.

The messages will be shown as .

Message	Problem	Solution
Messages in the body of the article
Invalid <ref> tag; refs with no name must have content	There is no content between the <ref>...</ref> tags.	Either put content between the <ref> tags (<ref>content</ref>), or (if you're reusing a named reference that's been defined elsewhere in the article) use a single tag <ref name="ref_name" />.
Invalid <ref> tag; refs with no content must have a name	A named reference has a malformed name.	This is produced by using the following markup or something similar: <ref />, which makes no sense to the software. To correct this error, create a full reference (<ref>content</ref>) or give the tag a name (<ref name="ref_name" />).
Invalid <ref> tag; invalid names, e.g. too many	A named <ref> tag has too many parameters	You can only specify two parameters, name= and group=. You can't, for instance, format a reference with <ref style="color:red;">content</ref>, or give it an id.
Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title	The name of the reference is a pure number. Disallowing this is intended to avoid naming conflicts, as unnamed references are automatically assigned numbers as names.	Rename the reference to contain at least one letter (eg <ref name="foo" /> instead of <ref name="123" />). It's good practice to give references meaningful names anyway. Make sure that when changing the name you update all the tags that refer to that reference!
Closing </ref> missing for <ref> tag	A reference is missing the closing </ref>.	Make sure that you are either using a closed pair of tags (<ref>content</ref>), or one single tag with a forward slash at the end to mark it as a single tag (<ref />)
Messages at the end of the article
Invalid <ref> tag; no text was provided for refs named $1	A single ref tag named "foo" (<ref name="foo" />) was invoked, but there is no full reference named "foo" (<ref name="foo">content</ref>) from which to get the reference text.	You may have misspelt the reference name, or used special characters that look the same but are actually different. For instance, <ref name="foo-bar">content</ref> and <ref name="foo–bar" /> are not the same: one contains a hyphen while the other uses an ndash. To avoid this sort of error, try to stick to the characters available on the standard keyboard. Alternatively, the full reference may have been removed from the article with other content. In this case the text of the reference will be available in the page history, and you can convert the single <ref /> tag into a full reference.
MediaWiki:Cite error references invalid input	The <references /> tag is malformed.	You need to ensure that the <references /> tag is properly formed.
Invalid <references> tag; no parameters are allowed. Use <references />	Parameters such as style= or id= were passed to the <references /> tag.
Invalid <references> tag; parameter "group" is allowed only. Use <references />, or <references group="..." />	The <references /> tag is malformed.
Cite error: <ref> tags exist, but no <references /> tag was found	The <references /> tag was not included at the end of the article.	Add the <references /> tag at the bottom of the article, below the last set of |ref= tags.
	The <ref> tag immediately before <references /> does not have a closing </ref>.	Fix the <ref> tag as explained above
	There are <ref>...</ref> tags after <references />.	Move the <references /> tag to below the last reference.
Ran out of custom backlink labels. Define more in the [[MediaWiki:Cite references link many format backlink labels]] message.	A named reference was used more than 702 times, thereby exhausting the list of available labels ("a", "b"... "aa", "ab"... "zy", "zz").	It should probably never be necessary to cite one source this many times. Consider whether some cites can be combined or removed, or edit MediaWiki:Cite references link many format backlink labels to add additional labels (maybe "aaa", "aab", etc).
<ref> tags exist for a group named "$1", but no corresponding <references group="$1"/> tag was found	The group parameter was used in a reference, but the corresponding <references /> tag was not included with a group parameter	Make sure that there is a <references /> tag on the page with the appropriate |group= parameter set.
	The reference immediately before <references /> does not have a closing </ref>.	Fix as for normal <references /> tags as explained above.
	There are <ref>...</ref> tags using a group after <references />.
Other messages
Internal error; invalid $str and/or $key. This should never occur.	Internal software error.	These messages should never occur. If you see them in articles, please contact the MediaWiki developers, who may be able to resolve the situation.
Internal error; invalid stack key. This should never occur.

Technical information

Internal messages are generated by the Cite.php extension and shown as a MediaWiki message. See the Parser hooks section of Special:Version for the installed version of Cite.php. These messages are in the MediaWiki namespace and can be modified only by admins.

Cite.php internal message	MediaWiki message
Cite error	Cite error: $1
Cite error key str invalid	Internal error; invalid $str and/or $key. This should never occur.
Cite error ref no input	Invalid <ref> tag; refs with no name must have content
Cite error ref no key	Invalid <ref> tag; refs with no content must have a name
Cite error ref numeric key	Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
Cite error ref too many keys	Invalid <ref> tag; invalid names, e.g. too many
Cite error references invalid parameters	Invalid <references> tag; no parameters are allowed. Use <references />
Cite error references invalid parameters group	Invalid <references> tag; parameter "group" is allowed only. Use <references />, or <references group="..." />
Cite error references no backlink label	Ran out of custom backlink labels. Define more in the [[MediaWiki:Cite references link many format backlink labels]] message.
Cite references link many format backlink labels	This is a list of the backlink labels used in the reference list, currently from a to zz
Cite error references no text	Invalid <ref> tag; no text was provided for refs named $1
Cite error included ref	Closing </ref> missing for <ref> tag
Cite error stack invalid input	Internal error; invalid stack key. This should never occur.
Cite error refs without references	Internal error; invalid stack key. This should never occur.
Cite error group refs without references	<ref> tags exist for a group named "$1", but no corresponding <references group="$1"/> tag was found

Reference table example

The following table is displayed here through the use of <references/>.