More or less. The way I learned it: hold the plumb bob against the groove under your knee cap (between patella and tibia), and it should go through the pedal spindle.

There are some variations.

I have to point out that I think the controversy and "myth" allegations over KOPS are stupid. It's just a traditional rule of thumb, and a good starting point. If someone prefers a different position, fine. Take it or leave it. I think it makes a whole lot less difference than saddle height, and many people (me included) shift around on the saddle all the time anyway.