• Predefined — A regular expression set included with the firmware. These match common data types. Cannot be modified except via FortiGuard, but can be copied and used as the basis for a custom data type. Can be used by both auto-learning profiles and input rules.

• Custom — A regular expression that you have configured to detect any data patterns that cannot be recognized by the predefined set. Can be modified. Can be used by input rules, but cannot be used by auto-learning profiles.