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The template <nowiki>{{</nowiki>[[{{ns:Template}}:{{BASEPAGENAME}}|{{lc:{{BASEPAGENAME}}}}]]<nowiki>}}</nowiki> inserts one or more invisible [[wikipedia:Fragment identifier|HTML fragment identifiers]] (anchor names) in a page. Those locations can then be linked to using <code><nowiki>[[#Location|...]]</nowiki></code> syntax {{#ifeq:{{BASEPAGENAME}}|Visible anchor|&nbsp;Unlike {{tl|Anchor}}, the first parameter will be visible text on the page.|}} (note that <code><nowiki>#Location</nowiki></code> here is not a browser instruction like <code><nowiki>#redirect</nowiki></code>—the word "Location" can be any word you wish to associate with any part of an article in which you decide to place the {{tlx|anchor}} template, and can be entirely arbitrary; also, the first letter of the ''location'' is usually capitalised to reflect the common capitalisation used in section headers).


{{anchor|Foo|Foo bar}}
== Examples ==

Common best practice (for section headers, the most common use case):<br />  <code style="color:darkgreen;"><nowiki>  {{</nowiki>anchor|Foo|Foo bar}}<br/>  == Examples ==</code> <br /> 


(This is actually used on this documentation page, so [[#Examples]], [[#Foo]] and [[#Foo bar]] all work.)<br/>

Reasons for the above being best practice are detailed in the following additional, numbered examples, as well as in  [[#Limitations|§&nbsp;Limitations]] below them:

# <code style="color:darkgreen;"><nowiki>{{</nowiki>{{lc:{{BASEPAGENAME}}}}|Foo<nowiki>}}</nowiki></code> <br /> could be linked to with <code><nowiki>[[#Foo|...]]</nowiki></code> from ''within the same article'' (let's call this article "Qux"), <br /> or it could be linked to with {{nowrap|<code><nowiki>[[</nowiki>Qux#Foo<nowiki>|...]]</nowiki></code>}} from ''other'' articles and from redirects (where the ellipsis after the word "Foo" here means the words chosen to represent that link in the Wikipedia article, which, of course, could be anything).
# Anchors can be more suitable for inter-article linking than section titles are, because anchors are more stable. For example a section title {{nowrap|1=<code>== Foo ==</code>}} within a Wikipedia article titled <code>Qux</code>: <br /> {{nowrap|1=<code style="color:dimgray;"><nowiki>==</nowiki>{{sp}}<code style="color:darkgreen;"><nowiki>{{</nowiki>{{lc:{{BASEPAGENAME}}}}<nowiki>|Foo bar}}</nowiki></code>{{sp}}Foo <nowiki>==</nowiki></code>}} <br /> Here, links via {{nowrap|1=<code><nowiki>[[</nowiki>Qux#Foo bar<nowiki>]]</nowiki></code>}} would remain valid even if the section were renamed {{nowrap|1=<code><nowiki>== {{anchor|Foo bar}} On foo and its many friends ==</nowiki></code>}}<br /> A drawback of this approach (as detailed in [[#Limitations|§&nbsp;Limitations]] below) is that having a template in the section header causes problems with the edit summary window each time that a section edit is done for this section. <br /> {{anchor|Example-note}}{{em|Note:}} The anchor is placed ''before'' the section name; otherwise browsers may hide the section title from view. Also, the anchor name (<code>Foo bar</code>) should be different than the section (<code>Foo</code>) to avoid invalid HTML.
# Within section titles, it may be preferable to simply use direct HTML, which may be achieved by [[wikipedia:substitution|substitution]] like this:<br /> {{nowrap|1=<code style="color:dimgray;"><nowiki>==</nowiki>{{sp}}<code style="color:darkgreen;"><nowiki>{{subst:anchor|Foo bar}}</nowiki></code> Foo <nowiki>==</nowiki></code>}}<br />which is saved into the article as:<br /> {{nowrap|1=<code style="color:dimgray;"><nowiki>==</nowiki>{{sp}}{{code|inline=y|1={{anchor|Foo bar}}}}{{sp}}Foo{{sp}}<nowiki>==</nowiki></code>}}<br />This provides the stable, linkable anchor, but without the edit problem.<br /> The [[#Example-note|Note]] above still applies. See [[#Limitations|§&nbsp;Limitations]] below for details.
# The template can be used to create multiple anchors with a single call. For example, <br /> {{nowrap|1=<code style="color:darkgreen;"><nowiki>{{</nowiki>{{lc:{{BASEPAGENAME}}}}<nowiki>|Foo|Bar|baz}}</nowiki></code>}} <br /> will create three anchors that can then be linked to with <code><nowiki>[[#Foo]]</nowiki></code>, <code><nowiki>[[#Bar]]</nowiki></code> and <code><nowiki>[[#baz]]</nowiki></code>.
# Here is a more literal example:<br /> Say you wrote an article about a recently discovered Indo-European language called "Yish Yash".  The title of your article would probably be "Yish Yash language" (if there were already an article titled "Yish Yash" that covered the culture generally).  Now let's say that within your article you wished to have a section titled "The placement of the tongue when producing Yish Yash vowel sounds". You would create a section heading that looked like this:<br />{{nowrap|1=<code><nowiki>== The placement of the tongue when producing Yish Yash vowel sounds == </nowiki></code>}}<br />Let's say that you then finished up writing and saved the new article. Now, say you came across another article on Wikipedia titled "Proto-Indo-European vowels" which happened to have a section on the unique tongue placement used in Yish Yash.  You decided it might be useful here for readers to be able to quickly access the section of your article on Yish Yash tongue placement when forming vowels; however, you don't want to send them to the beginning of the whole article on the Yish Yash language (you wanted to target them more specifically).  So you create a link in the Proto-Indo European vowel article to the ''section'' within ''your'' article on the placement of the tongue in Yish Yash: you might do so by editing the text of the Proto-Indo-European vowel article and adding something like this to a relevant place within it:<br />{{nowrap|1=<code><nowiki>[[Yish Yash language#The placement of the tongue when producing Yish Yash vowel sounds|Yish Yash tongue placement]] is particularly interesting.</nowiki></code>}}<br />That is some ''really'' long code, but it would create a direct link to the relevant section of the new Yish Yash language article and would look like this in the article on Proto-Indo-European vowels:<br /> "...<span style="color:blue;">Yish Yash tongue placement</span> is particularly interesting..." <br /> Now let's say another editor came along and wished to change the heading of this section of your article for some legitimate reason—perhaps to "Yish Yash vowels and the tongue".  They could do so by editing your article and making the section heading look like this:<br />{{nowrap|1=<code><nowiki>== Yish Yash vowels and the tongue ==</nowiki></code>}}<br />Unbeknownst to that editor, this would mean the link in the article on Proto-Indo-European vowels that you created earlier would now go by default to the top of the Yish Yash article instead of your carefully-chosen subsection!  However, if an ''anchor'' were placed within the section heading of the Yish Yash article either when you created it or when the other editor came along and changed it—perhaps something like this:<br />{{nowrap|1= <code><nowiki>== {{subst:anchor|Tongue}} The placement of the tongue when producing Yish Yash vowel sounds ==</nowiki></code>}}<br />or like this:<br />{{nowrap|1=<code><nowiki>== {{subst:anchor|Tongue}} Yish Yash vowel–tongue interaction ==</nowiki></code>}}<br />and the text of the article on Proto-Indo-European vowels had been changed by you to something like this:<br />{{nowrap|1=<code><nowiki>[[Yish Yash language#Tongue|Yish Yash tongue placement]] is particularly interesting.</nowiki></code>}}<br />then the link from the Proto-Indo-European article would continue to point to the relevant ''section'' of the Yish Yash article, even if the wording of the section heading there had changed completely and without the reader having to sort it out for themselves.  The use of anchors can make for a cleaner, more efficient Wikipedia reading experience where section headings are changed—which they not infrequently are.

=== Limitations ===

{|class="wikitable" style="float:right"
!Character
![[Character entity reference|Code]]
!Template
!Meaning
|-
|"
|<code>&amp;quot;</code> <br /><code>&amp;#34;</code>
|{{N/a}}
|(double)&nbsp;[[quotation mark]]
|-
|#
|<code>&amp;#35;</code>
|{{tl|hash}}
|[[Number sign|hash]]
|-
|&#124;
|<code>&amp;#124;</code>
|{{tl|!}}
|[[Vertical bar|pipe]]
|-
|&#61;
|<code>&amp;#61;</code>
|{{tl|{{=}}}}
|[[Equals sign|equals]]
|}
* Anchor names that contain any character shown in the table on the right will not work as expected. However, any of these characters can be replaced with the "&amp;#" codes shown for them here. Or, the pipe symbol and equals sign can be worked around with {{tl|!}} and {{tl|{{=}}}}, respectively. Markup code such as {{tag|sup|o}} and {{tag|sub|o}} (superscript and subscript) cannot be used. Most other characters, including white space and punctuation, are not a problem.
* Anchor names must be unique on a page, and must not duplicate any heading titles. Duplicate anchors will not work as expected since the <code><nowiki>#location</nowiki></code> links go to the first anchor with that name. Duplicate anchors result in invalid HTML; you can check for duplicate anchors by running the page through the [[wikipedia:W3C Markup Validation Service|W3C Markup Validation Service]].
* Anchor links are case-sensitive in '''some''' browsers, so treat all anchor links as case-sensitive when creating links to them. For example, if you create the anchor with <code><nowiki>=== {{anchor|Bar}} Baz ===</nowiki></code>, link to it with <code><nowiki>[[pagename#Bar]]</nowiki></code>, not <code><nowiki>[[pagename#bAR]]</nowiki></code>. However, because some browsers are '''not''' case-sensitive, do not create section titles or anchors that differ only in case from others on the page. That is, do not create both <code><nowiki>=== {{anchor|Baz}} Abcd ===</nowiki></code> and <code><nowiki>=== {{anchor|bAZ}} Efgh ===</nowiki></code>.
* If a template is inside a section title then the template code will appear in the edit summary window each time a section edit of that section begins, as in {{nowrap|1="<code><nowiki>/* {{anchor|Issues}}Limitations */ New issue</nowiki></code>"}}. The editor must manually fix the section title part of the edit summary window, or when the section is saved, the browser may not return to the section and the section link of that edit in the history page doesn't work. When using anchor in a section title, consider [[wikipedia:Substitution|substituting]] the template, resulting in <code>{{code|1={{anchor|...}}}}</code> being saved.

=== Use in tables ===
Anchors may be used within tables, subject to certain restrictions. The {{tlx|anchor}} template may be used in the caption and cells of a table, but not those portions of a table that are outside the caption and cells. It is used on the table's caption thus:
<syntaxhighlight lang=text>
|+ {{anchor|FooX}} A table caption
</syntaxhighlight>
and the following forms of cell are valid:
<syntaxhighlight lang=text>
!{{anchor|Foo1}} A header cell
!style="background:white;" |{{anchor|Foo2}} A header cell with styling
|{{anchor|Foo3}} A data cell
|rowspan=2 |{{anchor|Foo4}} A data cell spanning two rows
</syntaxhighlight>
You need to ensure that the {{tlx|anchor}} is not in that portion of the markup intended for the classes, styles etc. Thus, {{tlx|anchor}} cannot be placed anywhere on lines that begin with <code><nowiki>{|</nowiki></code> (start of table) or <code><nowiki>|-</nowiki></code> (new row), and the following forms of cell are not valid:
<syntaxhighlight lang=text>
!{{anchor|Foo1}} |A header cell
!style="background:white;" {{anchor|Foo2}} |A header cell with styling
|{{anchor|Foo3}} |A data cell
|rowspan=2 {{anchor|Foo4}} |A data cell spanning two rows
</syntaxhighlight>
If it is necessary for an anchor to be in any of these positions, a different technique is used—the <code>id=</code> attribute. This is placed in that portion of the markup where the classes, styles etc. may be used, as follows:
<syntaxhighlight lang=text>
{| id=FooX class=wikitable
|- id=FooY
!id=Foo1 |A header cell
!style="background:white;" id=Foo2 |A header cell with styling
|id=Foo3 |A data cell
|rowspan=2 id=Foo4 |A data cell spanning two rows
</syntaxhighlight>
The <code>id=</code> attribute may appear before, between or after any other attributes that may be present, but only one <code>id=</code> attribute may be used in each of these areas.

== TemplateData ==
{{TemplateDataHeader}}
<templatedata>{
"description": "The template {{anchor}} inserts one or more HTML anchors in a page. Those locations can then be linked to using [[#location|...]] syntax.  The parameters labels shown here (e.g., 'First anchor', '1', and the rest) are provided for convenience; no parameter label is required in the template itself, so you may create an anchor within an article by typing {{anchor|go here}} or {{anchor|this is it}} rather than {{anchor|First anchor=go here}} or {{anchor|1=this is it}} (though both formats will work correctly).  You may not use {{anchor}} all by itself, however, as this is like dropping a ship's anchor without tying a rope to it: it holds nothing in place, can't be found or used, and messes up the sea floor with garbage!",
"params": {
  "1": {
    "label": "First anchor",
    "description": "First anchor value; Only the first anchor is required.",
    "type": "string",
    "required": true
  },
  "2": {
    "label": "Second anchor",
    "description": "Second anchor.",
    "type": "string",
    "required": false
  },
  "3": {
    "label": "Third anchor",
    "description": "Third anchor.",
    "type": "string",
    "required": false
  },
  "4": {
    "label": "4th, 5th, ... anchor",
    "description": "For additional anchors, just add additional parameters (the template isn't limited to three)",
    "type": "string",
    "required": false
  }
}}</templatedata>

== See also ==
* [[wikipedia:ANCHOR]]
* [[wikipedia:TARGET]]
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