Setup USB exception list
If the Allow USB host storage setting is enabled, use this control to configure the use of one or more classes of USB devices or USB composite device on the mobile device. If the Allow USB host storage setting is disabled, any settings in this section have no impact. A USB Composite Device is a peripheral device that supports more than one device class. If you use this policy to control a USB Composite Device, ensure that you add all supported classes in the exception list.