MediaWiki:Tags/qqq

Shown on Special:Specialpages for page listing the tags that the software may mark an edit with, and their meaning. For more information on tags see MediaWiki.

It appears that the word 'valid' describes 'tags', not 'change'. It also appears that you could use the term 'defined' instead of 'valid', or perhaps use a phrase meaning 'The change tags that are in use'.