'Network usage' sets the app's age rating to 9+ (even it is a game for 6 year old).
Age rating descriptors are listed here - http://developer.nokia.com/resources...ge-rating.html
And they are explained here - http://developer.nokia.com/resources...scriptors.html
If you open the second link and go to the bottom of the page you can see the network usage explanation. But nothing specific to the web apps. Can we have simple web apps with 0+ rating?