Chapter 1 What’s New for FortiOS 5.2.1 : Usability Enhancements : Replacement Message Improvements
  
Replacement Message Improvements
The process of creating replacement message using tags and images has been simplified by the following additions:
A right-click menu to insert tags/images
An auto-complete feature for tags (when you begins by entering %%)
Descriptions for each tag that appear as they are typed
Image previews when an image tag is used
An graphics list that allows you to select from predefined images or upload a new image
Variables for source IP (%%SOURCE_IP%%), destination IP (%%DEST_IP%%), and user name (%%USERNAME%%) can now be added.