USB-A-PCB: Figure 6-9 (page 99) of the Universal Serial Bus Specification; Revision 2.0; April 27, 2000 USB-A-PCB: http://www.poweredusb.org/pdf/usb20.pdf # unofficial copy of the specification. We reference it here because the # original is in a ZIP, making access less convenient: # http://www.usb.org/developers/docs/usb_20_071012.zip