<type category="" namespace="" name="" is=""></type>
Some tags will automatically change the page.
The subcategories are defined by the wiki site. End users have no control over which subcategories show on the sidebar.
If you find a webpage that has no purpose and is clearly rubbish - do not use the
<removed>tag - instead, remove all of the content in the webpage and replace it with
<cat>removed</cat>then save it!