/ForestLevel:{ |2|3} The default forest functional level when creating a new forest is Windows 2000 (0); do not use this ...

/ForestLevel:{<0>|2|3} The default forest functional level when creating a new forest is Windows 2000 (0); do not use this switch when promoting a domain controller in an existing forest Specifies the forest functional level when creating a new forest. A value of 0 specifies Windows 2000. A value of 2 specifies Windows Server 2003. A value of 3 specifies Windows Server 2008.