USB has both power and data lines. This new standard can use data lines to negotiate power delivery, I believe. I'd expect will still be backwards-compatible of course. I would think the only allowable voltage would be 5V, as is currently.
http://www.usb.org/developers/powerdelivery/PD_1.0_Introduct... Page 9. There will be different voltage levels: 5V, 12V, and 20V.
USB has both power and data lines. This new standard can use data lines to negotiate power delivery, I believe. I'd expect will still be backwards-compatible of course. I would think the only allowable voltage would be 5V, as is currently.