Last Friday Ryan and I were playing Razz at the lunch game and in one hand he filled his wheel early. Was it 5th street? 6th street? Regardless, there was short conversation between us afterwards where he said he had "board lock" on his opponent (I think that opponent was me by the way). I seem to remember looking down and seeing that I had two wheel cards showing and I took issue with him saying that he had board lock since I too could possibly have had a wheel. He replied that with the wheel there was no way he was losing the hand which I obviously agree with. He had the nuts and clearly could not *lose* the hand.
But for some reason, don't know why, I had always defined board lock as the state where, based on the upcards of my opponents, everyone else's best possible hand is worse than mine. In other words, it's that they must have losing hands, not that I have a non-losing hand. I think that board lock would realistically only apply for low hands since high hands could always end up being totally hidden Quads.
Furthermore another condition that I had assumed was part of board lock was that it is good for the remainder of the hand. If you have the Nut Flush on the Turn in Hold'em, your nut hand is vulnerable in case the board pairs. The way I see board lock, if you achieve board lock for low on 5th street (i.e. you have the wheel versus pair of Sevens and a Six) then you can jam at every opportunity knowing that there is no way that anyone can catch up to you since based on the upcards they cannot beat you or even tie you.
I think board lock would also apply to PtT when you are going for low with a crappy J high but you see the other two players in the hand showing pairs after the second flip. As soon as you see that happen you have a green light to raise knowing you are a lead pipe cinch for low.
Anyway, still doing research on the matter. The other thing I wanted to mention was that while Googling for "'board lock' poker" the TNP blog showed up in the #2 spot!