Board Thread:Support Requests - Designing Your Wiki/@comment-33688175-20200317170752/@comment-9605025-20200321050026

Okay. I think I see the issue. But first, let me clarify what "transclusion" means. "Transclusion" is the act of including something or part of something in something else. If you want to know more about transclusion as it pertains to computer science as a whole, you can have a look at the Wikipedia page. MediaWiki (the platform used to host Fandom wikis) uses this concept with regards to page content. You can read this page to learn more about transclusion as it pertains to MediaWiki. Templates are simply pages in a particular namespace. The intent of the namespace is to have pages that are intended to be transcluded on other pages. There isn't any code that can be used on templates only and pages in other namespaces can be trancluded as well. So, basically, the only thing that makes templates unique as a page type is the namespace.

Now on to the navbox problem. There are two distinct parts to trancluding a page (template or otherwise). First, you need to determine the content of the page. Second, you need to determine where that content should be transcluded. The code you have been placing on Template:Navbox is not code for determining page content but code for transcluding the content.

So what you are telling MediaWiki is that you want Template:Navbox to contain the content of Template:Navbox. Okay, what is that content? Well to find out, let's look at Template:Navbox. Oh, it is the content of Template:Navbox; what is that? The content of Template:Navbox... I assume you have spotted the problem by now.

If you want to create nested navboxes for your main page, you need to create a new template. Let's call it "Template:MainPageNavbox". Then your contents of Template:MainPageNavbox would be what you have been trying to change Template:Navbox to. Something like this from your previous post.