Chapter 10 Install and System Administration for FortiOS 5.0 : Using the CLI : Command syntax
  
Command syntax
When entering a command, the command line interface (CLI) requires that you use valid syntax and conform to expected input constraints. It will reject invalid commands.
Fortinet documentation uses the following conventions to describe valid command syntax
See Also
Terminology
Indentation
Notation
Connecting to the CLI
Sub-commands
Permissions
Tips