The USB Power Delivery specification defines a power delivery system covering all elements of a USB system including USB Hosts, USB Devices, Hubs, Chargers and cable assemblies. This specification describes the architecture, protocols, power supply behavior, connectors and cabling necessary for managing power delivery over USB at up to 100W in SPR Mode and 240W in EPR Mode. This specification is intended to be fully compatible with and extend the existing USB infrastructure. It is intended that this specification will allow system OEMs, power supply and Peripheral developers adequate flexibility for product versatility and market differentiation without losing backwards compatibility. USB Power Delivery is designed to operate independently of the existing USB bus defined mechanisms used to Negotiate power which are: «&[USB 2.0], [USB 3.2] in band requests for high power interfaces. «&[USBBC 1.2] mechanisms for supplying higher power (not mandated by this specification). «&[USB Type-C 2.4] mechanisms for supplying higher power. Initial operating conditions remain the USB Default Operation as defined in [USB 2.0], [USB 3.2], [USB Type-C 2.4] or [USBBC 1.2]. «&The DFP sources vSafe5V over VBUS. «&The UFP consumes power from VBUS. This specification is intended as an extension to the existing [USB 2.0], [USB 3.2], [USB Type-C 2.4] and [USBBC 1.2] specifications. It addresses only the elements required to implement USB Power Delivery. It is targeted at power supply vendors, manufacturers of [USB 2.0], [USB 3.2], [USB Type-C 2.4] and [USBBC 1.2] platforms, devices and cable assemblies. Normative information is provided to allow interoperability of components designed to this specification. Informative information, when provided, illustrates possible design implementation.