Board Thread:Support Requests - Getting Technical/@comment-45310000-20200418011510/@comment-9605025-20200420064727

Transclusion

Fandom does not allow you to transclude anything that is not from the local wiki. The one exception is pages from Community Central. However, this exception has not yet been implemented for UCP wikis. Per the most recent tech update, they attempted to release an implementation of this but had to immediately disable it due to some bugs.

I am curious to see if Fandom adds this stringent transclusion rule to Gamepedia. They plan on eventually converting Gamepedia to UCP as well but Gamepedia wikis currently enjoy more or less complete freedom when it comes to interwiki prefixes and interwiki transclusions. Fandom wikis are the complete opposite; staff must approve all changes.

File MIME Type

Again, the issue is that none of the file information is avaialble to wikitext-level "functions". As far as wikitext is concerned, it is just taking your word that such a file exists. It is only once wikitext gets parsed that the actual file is even checked for; never mind extracting data from.