Users will get an exception page for multiple reasons, one such reason is because a policy decision has denied access to the site based on some criteria or other. Often knowing the rule that caused the exception page to be presented can help speed up and simplify the troubleshooting process.
As of SGOS 220.127.116.11 Blue Coat added the ability to track rules within policy trace by the use of policy reference ID.
Unfortunately as of SGOS 6.5.9.x and 6.6.4.x this ID cannot be used within an exception page.
Blue Coat is looking at the possibility of implementing this feature in a later release of SGOS