Chapter 15 Unified Threat Management for FortiOS 5.0 : Intrusion protection : Configure IPS options : Extended IPS Database.
  
Extended IPS Database.
Some models have access to an extended IPS Database. The extended database may affect the performance of the FortiGate unit so depending on the model of the FortiGate unit the extended database package may not be enabled by default. For example, the D-series Desktop model have this option disabled by default.
This feature can only be enbled through the CLI.
config ips global
set database extended
end