Chapter 15 Unified Threat Management for FortiOS 5.0 : Intrusion protection : IPS concepts : Signature-based defense : Custom/predefined signature entries
  
Custom/predefined signature entries
Signature entries allow you to add an individual custom or predefined IPS signature. If you need only one signature, adding a signature entry to an IPS sensor is the easiest way. Signature entries are also the only way to include custom signatures in an IPS sensor.
Another use for signature entries are to change the settings of individual signatures that are already included in a filter within the same IPS sensor. Add a signature entry with the required settings above the filter, and the signature entry will take priority.