SourceWatch:Template documentation

Templates are a very powerful feature of MediaWiki, but can be confusing to new users, and even experienced users can have difficulty making sense of the more complex ones. Templates should therefore be accompanied by documentation to improve usability.

Template documentation should explain what a template does and how to use it. It should be simple enough that a user without complete knowledge of the intricacies of template syntax – which includes many experienced contributors who focus their attention elsewhere – can use it correctly. This is especially true in the case of very widely-used templates.

What to include
Documentation should cover:


 * The basic purpose of the template: what it does, and (if it is not immediately obvious) why it needs to be done. If there are other templates with similar names or purposes, it's a good idea to mention those, to reduce the chance of the wrong one being used.
 * Any parameters that the template takes. Explain whether they are numbered or named, whether they are optional (and if so, what the default value is), and what effect they have. If a parameter can take only a limited set of values (“yes” or “no”, for example), must be a number, or is constrained in some other way, this should be made clear.
 * Usage examples. Specify the exact wikitext that should be used, and the result it produces. The wikitext can be enclosed in a container to make it clear and  . If the template can be used in several different ways (with or without optional parameters, for example), provide a range of examples. A good way to do so is to transclude the template itself into the documentation a few times (i.e., use live examples), with different parameters each time, and list the parameters used in each case.
 * Related templates. If the template is one of a series of templates, include links to these – in particular, ensure that every template in the series is linked from each of the others, as this makes navigation easier. (A separate navigation template may be useful for this purpose; see for example Template:Protection templates).
 * Appropriate categories and interwiki links, where applicable. Like the documentation, these must be within a container. Many template categories are available, go to Category:Sourcewatch templates to browse through them.

Template documentation is often placed in a subpage of the template itself, which is then transcluded at the end of the template page. This separates the often complex template code from the documentation, making the documentation easier to edit. It also allows templates to be protected where necessary, while allowing anyone to edit the documentation. This method is sometimes referred to as the “template doc page pattern”.

Documentation of any sort on a template page should always be enclosed by a container, so that it does not show up when the template is used on another page. Text on the template page itself adds to the amount of text which must be processed when displaying the template, which is limited for performance reasons. Placing the documentation in a subpage avoids this (MediaWiki developers have recommended it for this reason).

How to create a documentation subpage
Documentation subpages should be named and formatted using the following general pattern, for consistency.

Suppose your template is named. Create a subpage with the name. See the details at Documentation or copy-paste the following wikitext as a start for your documentation:

Usage
&lt;includeonly>

&lt;/includeonly>

The top line will display a message explaining the current page, and linking to the documented page.

Insert the documentation after the top line, and categories and interwikis under the appropriate comment line – leaving the comment in place so that the layout is preserved when the page is edited in future. The subpage template sets a  ensuring that a  will be properly sorted at "X" and not "T", it is thus not useful or desirable to add a  sortkey to the categories.

Save the subpage, and return to the template itself,  in this example. Edit the template and append the following at the end of the template code:

&lt;noinclude>

&lt;/noinclude>

This will transclude Documentation at the bottom of the template page.

Important: Make sure the opening  begins on the same line as the last character of the template code (or text), and not on a new line. Otherwise, extra space will be inserted below the template when it is used, which is usually not wanted.

If the template is already protected, ask an administrator to do this, or request an edit by using an Editprotected on the template's talk page. If documentation, categories and interwiki links already exist in a section enclosed within a container, move them into the documentation subpage, as it is best not to have documentation split across two separate pages.

If the code is put on the template page first, one can benefit from the preload feature to get a pre-filled doc page skeleton: if the documentation page does not exist yet, clicking the edit link on the template page will preload the contents of Documentation/preload into the editbox of the /doc subpage creation.

You may wish to redirect the talk page of the /doc subpage to the talk page of the template itself. Then all talk relating to the template and its documentation will end up on the same talkpage. For example, redirect  to.

Example
See the heavily-used Template:Cite web for an example of detailed template documentation. Note that the template itself is protected, but the documentation subpage, Template:Cite web/doc is unprotected and can still be edited.

/sandbox and /testcases
Before doing changes to a template it can be good to first copy the template code to a sandbox and run some testcases, since the template might be visible on thousands of pages. If you create subpages named exactly "/sandbox" and "/testcases" to a template then the green box on the template auto-detects this and will show links to those pages in its header.

Several templates, one documentation page
When several templates work together or are very similar then it is often clearer and easier to maintain one single documentation page that documents them together. The simplest way to do this is to make a full documentation page at one of the templates, and then make "soft redirects" from the other templates. That is, to make very short documentation pages at the other templates that have only one or two sentences that states where the full documentation can be found and link to it. See for instance wrap.