(the wikitext below is essentially the exact wikitext I used on both test wikis, minus the page names; I performed both tests using a root page of `Template:Inclusion control test`)
**Steps to replicate the issue** (include links if applicable):
* Create a test template with the content
```
{{big|{{strong|Copyright attribution: all descriptions of inclusion control tags are based on [[w:Special:Permalink/1337167814]].}}}}
This is a test of whether other inclusion control tags function '''inside''' <code><nowiki><onlyinclude></onlyinclude></nowiki></code> tags.
{{cot|Long-winded explanation}}
{{slink|w:Help:Template#Inclusion control: noinclude, includeonly, and onlyinclude}} says that the <code><nowiki><onlyinclude></onlyinclude></nowiki></code> tags create a situation where "nothing on the page except what appears between the tags is included when the template is called". See the reference beside this sentence for a description of the other inclusion control tags.<ref><code><nowiki><noinclude></noinclude></nowiki></code> tags cause the wikitext between to be processed when the source page is viewed or saved, but not upon transclusion/substitution of the source page. <code><nowiki><includeonly></includeonly></nowiki></code> tags, on the other hand, cause the wikitext to be processed only upon transclusion/substitution and not when the source page is viewed or saved.</ref> As evidence, <code><nowiki><includeonly>includeonly text</includeonly><onlyinclude>onlyinclude text</onlyinclude><noinclude>noinclude text</noinclude></nowiki></code> is provided. Notice that "onlyinclude text" and "noinclude text" appear on the source page; however, only "onlyinclude text" appears during transclusion/substitution. "includeonly text" never appears throughout the process as it is overridden by the <code><nowiki><onlyinclude></onlyinclude></nowiki></code> tags.
{{cob}}
The idea is that <code><nowiki><noinclude></noinclude></nowiki></code> and <code><nowiki><includeonly></includeonly></nowiki></code> might work ''within'' <code><nowiki><onlyinclude></onlyinclude></nowiki></code> tags. To test this, I will use the wikitext <code><nowiki><onlyinclude>This is<noinclude> the source page of</noinclude> a [[(**full page name of your choice**)|test template]]<includeonly> {{safesubst:<noinclude />ifsubst|that has been substituted|being transcluded}}</includeonly>.</onlyinclude></nowiki></code>; below is the wikitext in action.
<onlyinclude>This is<noinclude> the source page of</noinclude> a [[(full page name)|test template]]<includeonly> {{safesubst:<noinclude />ifsubst|that has been substituted|being transcluded}}</includeonly>.</onlyinclude>
I will [[w:Help:Transclusion|transclude]] and [[w:Help:Substitution|substitute]] this template on the subpage [[/test subpage]] to see whether this trick functions.
== Notes ==
{{reflist}}
```
* Click on the `[[/test subpage]]` redlink and create it with the following content:
```
See the [[Template:Inclusion control test|root page]] for why this subpage exists.
A reminder: the wikitext processed here is <code><nowiki><onlyinclude>This is<noinclude> the source page of</noinclude> a [[(name of root page)|test template]]<includeonly> {{safesubst:<noinclude />ifsubst|that has been substituted|being transcluded}}</includeonly>.</onlyinclude></nowiki></code>.
Transclusion: {{(name of root page)}}
Substitution: {{subst:(name of root page)}}
```
**What happens?**:
On the subpage, the transclusion shows "onlyinclude textThis is a test template being transcluded.This is a test template being transcluded." when read
The substitution shows "onlyinclude textThis is a test template that has been substituted.This is a test template that has been substituted."
**What should have happened instead?**:
The transclusion should have shown "This is a test template being transcluded."
The substitution should have shown "This is a test template that has been substituted."
**Software version** (on `Special:Version` page; skip for WMF-hosted wikis like Wikipedia): N/A
**Other information** (browser name/version, screenshots, etc.):
Browser: Google Chrome, Version 144.0.7559.133 (Official Build) (arm64)