Thread:UltranovaXL/@comment-4220590-20170517160635/@comment-4220590-20170517161917

A grandparent category is what we call a category that has been given to a category that already has a category underneath another category.

Take for example Category:Sonic the Hedgehog 3 zones. As you can see, it has the categories "Sonic the Hedgehog 3" and "Game stages". We give the category "Sonic the Hedgehog 3 zones" to any Zone in Sonic the Hedgehog 3. If we give "Sonic the Hedgehog 3 zones" to Angel Island Zone, then everything is okay. However, that means you cannot add the categories "Sonic the Hedgehog 3" or "Game stages" to Angel Island Zone despite it appearing in Sonic 3 and it being a level. That is because "Sonic the Hedgehog 3 zones" has the categories "Sonic the Hedgehog 3" and "Game stages". Adding any of these categories Angel Island Zone is considered what we call "Grandparent categories". It is also for the same reason that we do not give Angel Island Zone the "Game information" category - because "Game stages" has the category "Game information"

If you want to avoid this in the future, please check the categories before you add them.