On the Pro Mini what are the pins in the corners labelled GRN and BLK?
I bet that should go in the never ask questions.
Green and black? , No idea, but guess Black meaning negative and green , the green led.
I looked at the Pro Mini's schematic. I would say that is JP1 in the schematic, correct? BLK is ground and GRN is DTS. I think that is the color of the wire used in the recommended FTDI cable.
SirPoonga is correct. It is for the FTDI cable on which 1st and 6th pins are black and green. It's so you don't plug in the FTDI cable in wrong orientation.