Maybe not the right forum for this, but ...

I have just repaired a Asus T100 tablet for a friend. The point of interest for me is the charger port, which uses a micro-usb connector (like lots of stuff these days). The markings on the device give the voltage rating for this port as 9V, which is also repeated in the user manual found on line.

Now, for all these years I have believed that usb voltage is 5V. I don't have the original charger that came with the tablet so can't verify the 9V. But it seems to suggest that not all chargers feeding a usb cable are limited to the standard 5V. It sounds very dangerous to me, that a user could accidentally plug a 9V supply into a device that is expecting only 5V.

From the Asus manual:

Any thoughts?