The R80+ Protocol Signature & Protocol settings on the service objects are the source of a lot of confusion but as Val said is mostly separate from Application Control. Understanding the ramifications of enabling the Protocol Signature setting beforehand is highly advisable. This seems to be one area that does not have a lot of documentation, so I took my best shot at trying to explain it in my unpublished "APCL/URLF Immersion" class for a private customer. Whether I did a good job or not is left as an exercise for the reader, see below. 😀
Gateway Performance Optimization R81.20 Course
now available at maxpowerfirewalls.com