X, GND, and 5V need to be manually connected to their relevant pin location (if you want to use them). They are there simply so that I do not have to remember the pin location for those two things. I would connect them and now I would know their location. X would be whatever single pin you are trying to test.

This is meant to be used with a logic level translator and a FPGA to get various video outputs from PPUs. It may have other uses.