33class_alias( SkinSubPageSubtitleHook::class,
'MediaWiki\\Hook\\SkinSubPageSubtitleHook' );
This is one of the Core classes and should be read at least once by any new developers.
This is a hook handler interface, see docs/Hooks.md.
onSkinSubPageSubtitle(&$subpages, $skin, $out)
This hook is called at the beginning of Skin::subPageSubtitle().