Chapter 3 Authentication for FortiOS 5.0 : Users and user groups : User groups : SSO user groups
  
SSO user groups
SSO user groups are part of FSSO authentication and contain only Windows or Novell network users. No other user types are permitted as members. Information about the Windows or Novell user groups and the logon activities of their members is provided by the Fortinet Single Sign On (FSSO) which is installed on the network domain controllers.
You can specify FSSO user groups in identity-based security policies in the same way as you specify firewall user groups. FSSO user groups cannot have SSL VPN or dialup IPsec VPN access.
For information about configuring FSSO user groups, see “Creating Fortinet Single Sign-On (FSSO) user groups”. For complete information about installing and configuring FSSO, see “Agent-based FSSO”.