Both In is for having both ethernet and the IO behind the rack ear. I use this configuration to mount the NanoKVM to the back of a rack and use keystones to pass through all the IO and Ethernet through my patch panel. 

Eth Out is for having the ethernet port facing out when mounted to the rack. Probably best used if you are controlling a device mounted to the rack itself and only need to patch the ethernet to a switch. 

IO Out is for having the IO face out when mounted to the rack. Probably best used if you are controlling an external device, such as a laptop next to the rack. 

Same print orientation as the original.