WordPress at a glance
action is not described

_user_admin_menu action-hook . WP 3.1.0

Fires before the administration menu loads in the User Admin.

The hook fires before menus and sub-menus are removed based on user privileges.

Usage

add_action( '_user_admin_menu', 'action_function_name_4679' );
function action_function_name_4679(){
	// action...
}

Where the hook is called

In file: /wp-admin/includes/menu.php
_user_admin_menu
wp-admin/includes/menu.php 30
do_action( '_user_admin_menu' );

Where the hook is used (in WP core)

Does not used.