Pushing that tag end through the loop of dental floss and then pulling it back under the wraps you just created is the only thing that will complete the knot. If you don't do that, there's nothing to keep the wraps there; it will just unravel or unwind as soon as you let it go with your fingers. The first time you do it, you'll see...

I prefer this method to the one which Big John mentioned right after my post because I can slide this one up and down the center serving until I determine its final resting spot, and then pull hard on the tag ends to lock it down. I used to tie my nock sets in with half-hitches like John does (and there's certainly nothing wrong with that; I've seen some of the country's best tuners use that exact method), but this offers me more flexibility in moving the nock until I get it where I want it.

And thanks for the kind words; they are indeed appreciated. It's what makes doing a big thread like this worthwhile. Well, that... and all the money Justinpays me. [:-]