Zero Clearance valve lash ?

I uderstand this method of adjustment except for the preload direction. On the solids it's a gap and on the hydraulics your saying it's negative which would just start opening the valve while setting the lifter prelaod. Strange because in my minds eye the valve must close completely. It is confusing to me but I do believe in the mechanical sense that I have it right. Right now I have them set to zero clearance just before the valve opens and then backed off 1/2 turn which puts the negative on the lifter plunger rather than opening the valve. Even on the solids the valve closes completely. So confusing yes. So .020, 20 thousand's of a inch is a negative factor that is set at the lifter plunger right? Not at opening the valve past zero clearance. Also my saying zero clearance may be confusing everyone else into mistaking it for lash. My zero clearance means right before the valve opens, so to add to that would open the valve!
I've also read to set the rockerarm system to (zero lash) then turn the adjuster an additional 1 & 1/2 turns, hah, I haven't tried that one yet. I personally like zero clearance myself, but want to do it right. I built a 400 Pontiac once and it set at zero clearance. I built a HO 305 once with roller lifters and set them at zero clearance. Both ran excellent! Built the little 273 Mopar with adjustable rockers but that was a solid lifter build and it ran excellent! Everything else Mopar I built has been the stock 1.5 ratio hydraulic system which is a sinch!