Chapter 15 Unified Threat Management for FortiOS 5.0 : Data leak prevention : Data leak prevention concepts : File filter
  
File filter
File filters use file filter lists to examine network traffic for files that match either file names or file types. For example, you can create a file filter list that will find files called secret.* and also all JPEG graphic files. You can create multiple file filter lists and use them in filters in multiple DLP sensors as required.