User blog comment:Wildoneshelper/My reasons to put "artillery", "cavalry" categories into units riding elephants/@comment-127769-20140205133958

perhaps you must read the proposal I made to the user X~Calibur95. here: http://ageofempires.wikia.com/wiki/User_talk:X~Calibur95.

most articles don't need to have more than 5 categories, but there are exceptions.