Manual:$wgSpecialPages

Details
$wgSpecialPages stores a list of custom special pages defined for a MediaWiki installation. The array is keyed by a non-localized id for the special page. The value assigned to each key is an specifier (MediaWiki 1.34+), or one of the following:


 *  string:  a string containing the name of a subclass of .
 *  array:  an array where the first element is the name of the subclass and all remaining elements are parameters that should be passed to the constructor of that subclass. ( This format was deprecated in MW 1.18 and is no longer recognized as of MW 1.32. )
 *  callback:  since MW 1.24,  expected to return a   instance.  Useful for full control over the special page's construction parameters.
 * an actual SpecialPage object.

A special page can also be disabled by using:

For more information, please see SpecialPage.php