User blog comment:Rappy 4187/Technical Update: November 2, 2015/@comment-11733175-20151104095739

While a custom-* prefix is a step in the right direction, it shows a surprising lack of knowledge of extensions installed on Wikia that have hardcoded prefixes:
 * Gadget-* is used to control all gadget related messages, such as descriptions, headers and names. The JS Review process already handles the .js files, so why not open up the rest of these messages? Gadgets-definition would be nice to have as well.
 * Tag-* can be used in AbuseFilter to define custom tags to be applies to changes (edits and log actions). It's possible that tag messages added by extensions could fall afoul of this, but out of the standard 5 I can find on w:c:rs:SpecialTags 3 are from VE, 1 is from TorBlock and 1 is from Wikiamobile/Mercury. I sincerely hope all of those have been properly escaped.

I'm sure there's more as well.