This happens because there is an error in the Command Line Interface (CLI) Help. When the CLI Help is accessed on a Cisco IOS router, the aaa authorization network command could appear as shown:
Router(config)#aaa author network ? default The default authorization list.
The aaa authorization network command is supported, as shown, by default and for a named list authorization.
aaa authorization network group radius local
For more information, refer to the Named Method List Configuration section of Configuring Authorization.