This specification is intended as an extension to the existing [USB 2.0], [USB 3.1], [USB Type-C 1.2] 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 3.1], [USB Type-C 1.2] 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, may illustrate possible design implementation.