Asus Transformer Pad (TF701T) - Manual (Page 27)

K00C 
Left view
USB Dock port
This 36-pin USB Dock port allows you to supply power to your ASUS
mobile dock and charge the internal battery pack. You can also charge
your ASUS Tablet and ASUS mobile dock assembly using this port.
Battery charge indicator
This two-color LED provides a visual indication of the battery’s charge
status.
Refer to the table below for details:
Color Status
Green Fully charged.
Orange Charging mode.
OFF The ASUS mobile dock is not plugged to a power source.