Manual:$wgAjaxExportList

Details
Registry for functions callable via Ajax. This is a way for extensions (and some functions) to make functions callable from JavaScript. Making an Ajax request to   with the   parameters will result in a   call in PHP, as long as funcname is listed in  . Such functions then usually return an AjaxResponse object.

 and  cause <tvar|3> </> and <tvar|4> </> to be added to this array, respectively.