Editing Help:Transclusion (section)

===Markup===
{{also|Help:Template#Noinclude, includeonly, and onlyinclude|Help:Category#Categories and templates}}

In transclusion, a source page is transcluded into a destination page. But with partial transclusion, only part of that source page will be transcluded into a destination page. But in addition, what is transcluded to a destination page does not have to be visible on the source page.

''Page rendering'' of a source page can be defined as the rendering of that source page when it is saved, which will be the same as the [[WP:preview|preview]].  We can call this rendering '''''here'''''.

''Transclusion rendering'' of a source page can be defined as the rendering of a destination page that has a source page transcluded into it; but only that part of the destination page that was transcluded from the source page. The preview of the transclusion rendering will again be identical. We can call this rendering '''''there'''''.

There are three pairs of tags involved in cases where page rendering ''here'' should differ from transclusion rendering ''there''. As described earlier, these are {{tag|noinclude|o}}, {{tag|includeonly|o}} and {{tag|onlyinclude|o}}. These tags are invisible, but affect both page rendering ''here'' and transclusion rendering ''there''. These tags pair-off to demarcate sections that will create differences. Each tag will describe exceptions to transcluding the whole page named.

<pre>
<noinclude>  This section is visible here; but this section is not visible there. Sections outside of these tags will be visible both here and there. </noinclude>

<onlyinclude> This section is visible here; this section is also visible there. Sections outside of these tags will be visible here, but will not be visible there. </onlyinclude> 

<includeonly> This section is not visible here; but it is visible there. Sections outside of these tags will be visible both here and there. </includeonly></pre>
{| class="wikitable" style="text-align: center;"
! Wikitext
! What is rendered ''here'' (source page)
! What is transcluded ''there'' (destination page)
|-
|{{tag|noinclude|content=text1}} text2
|<code>text1 text2</code>
|<code>text2</code>
|-
|{{tag|onlyinclude|content=text1}} text2
|<code>text1 text2</code>
|<code>text1</code>
|-
|{{tag|includeonly|content=text1}} text2
|<code>text2</code>
|<code>text1 text2</code>
|}
An important point to note is that {{tag|noinclude|o}} and {{tag|onlyinclude|o}} do not affect what is page rendered ''here'' at all, unlike {{tag|includeonly|o}}. The {{tag|noinclude|o}} tags stops text inside the tags being transcluded ''there'', while {{tag|onlyinclude|o}} has the opposite effect: it stops text outside of the tags from being transcluded ''there''.

Only {{tag|includeonly|o}} stops text from being page rendered ''here''. But naturally enough it is transcluded ''there''. Text outside of the tags will be both rendered ''here'' and transcluded ''there''.

There can be several such sections. Also, they can be nested. All possible differences between ''here'' and ''there'' are achievable. 

One example is a content editor who picks an {{tag|onlyinclude|o}} section, and then takes a {{tag|noinclude|o}} section out of that; but then picks out yet another {{tag|onlyinclude|o}} section to append to ''there''; but none of this affects their article in any way.
 
Another example is the template programmer, who will {{tag|includeonly|o}} the code section and {{tag|noinclude|o}} the documentation section of a page.