Chapter 20 Virtual FortiGate Units for FortiOS 5.0 : FortiGate VM Overview : Deployment package contents
  
Deployment package contents
Citrix XenServer
The FORTINET.out.CitrixXen.zip file contains:
fortios.vhd: the FortiGate VM system hard disk in VHD format
fortios.xva: binary file containing virtual hardware configuration settings
in the ovf folder:
FortiGate-VM64.ovf: Open Virtualization Format (OVF) template file, containing virtual hardware settings for Xen
fortios.vmdk: the FortiGate VM system hard disk in VMDK format
datadrive.vmdk: the FortiGate VM log disk in VMDK format
The ovf folder and its contents is an alternative method of installation to the .xva and VHD disk image.