Requested feature overview description.
A tag categorisation ( like "Artist", "Copyright", "Character" etc.) but for "Metadata". [Idea from Gelbooru.com]
Tags like file format, animated, censored, (source_/..._)request, high/lowres, audio etc. belong in here - anything that does not really have to do with the picture itself but with it's meta properties.

Why would it be useful?
I think it really comes in handy having an overview of these properties. Short and quick. Swiftly being able to check: Does the file supposed to have sound? Is the software SFM or Blender? Which file format was this again? And whatever useful information you can put into such tag group. Normal tags are there to describe what is going on the picture itself so you can easily in-/exclude it in your search, and I don't think that's necessarily the case with these meta-tags.

What part(s) of the site page(s) are affected?
The tag list next to the image.(Re)grouping of existing tags will be necessary.