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What is USB3.1 Type C?

A January 2013 press release from the USB group revealed plans to update USB 3.0 to 10 Gbit/s.
 The group ended up creating a new USB version, USB 3.1, which was released on 31 July 2013,
introducing a faster transfer mode called "SuperSpeed USB 10 Gbit/s", 
putting it on par with a single first-generation Thunderbolt channel. 
The new mode's logo features a "Superspeed+" caption (stylized as SUPERSPEED+). 
The USB 3.1 standard increases the data signaling rate to 10 Gbit/s in the USB 3.1 Gen2 mode, 
double that of USB 3.0 (referred to as USB 3.1 Gen1) and reduces line encoding overhead to just 3% by changing the encoding 
scheme to 128b/132b. The first USB 3.1 implementation demonstrated transfer speeds of 7.2 Gbit/s.
The USB 3.1 standard is backward compatible with USB 3.0 and USB 2.0.

USB Type-C is a specification for a reversible-plug connector for USB devices and USB cabling. 
The Type-C plug connects to both hosts and devices, replacing various Type-B and Type-A connectors and cables
 with a standard meant to be future-proof, similarly to Apple Lightning and Thunderbolt.
The 24-pin double-sided connector provides four power/ground pairs, two differential pairs for USB 2.0 data bus
 (though only one pair is implemented in a Type-C cable), four pairs for high-speed data bus, 
two "sideband use" pins, and two configuration pins for cable orientation detection, 
dedicated biphase mark code (BMC) configuration data channel, and VCONN +5 V power for active cables.
Type-A and Type-B adaptors/cables will be required for older devices in order to plug into Type-C hosts; 
adaptors/cables with a Type-C receptacle are not allowed.

Full-featured USB Type-C cables are active, electronically marked cables that contain a chip with an ID function 
based on the configuration data channel and vendor-defined messages (VDMs) from the USB Power Delivery 2.0 specification. 
USB Type-C devices also support power currents of 1.5 A and 3.0 A over the 5 V power bus in addition to baseline 900 mA; 
devices can either negotiate increased USB current through the configuration line, 
or they can support the full Power Delivery specification using both BMC-coded configuration line and legacy BFSK-coded VBUS line.