I have noticed that some values in settings.bundle (Root.plist) do not allow you to associate a default value with them?

Is there a way to add a default field or is it simply a case of adding the appropriate defaults for these items inside the application using …
NSDictionary *defaultSettings = [NSDictionary dictionaryWithObjectsAndKeys:@"Kinetic", @"IDBombs", nil];
[userDefaults registerDefaults:defaultSettings];
Just curious if I am doing this right or missing something?
Right mouse click on any row within the item, click
Add rowon the menu and chooseDefault value.