Pin 7 is the same as doing the following per the guide below using Pad A in the diagram section.
Looking at the BMPOA Build Document schematic you will see that by placing the Tone TwEQ in Pad A you are now bypassing everything downstream from Pad A which is the Tone section and Volume Pot for which the Tone TwEQ will now take over for both.
The Tone TwEQ is now a Plug & Play Active Tone Control & Volume for your BMPOA. Very clever IMHO.
Incidentally several other boards include A/B pads for experimentation as well.