Missing User Guide page -- Exceptions class

[eluser]JensRoland[/eluser]
In the /system/libraries/ folder (CI 1.7.0), I notice there is an Exceptions.php file. Inside, it refers to a user guide page that doesn't exist:

http://ellislab.com/codeigniter/user-gui...tions.html

I've even searched the site, and there's no reference to using CI exceptions anywhere