The PosiLocks name is a set that I have been using for over 25 years on my Hipo. The name most likely originated as something that has the same connotation as Positraction differentials as used in some rear ends. A Positraction differential differs from our Traction Locks and Equa Locks in Fords as they have ramps that force the side gears to positively lock up the clutches rather than depending on springs for preloading the clutches. PosiLocks and PolyLocks are just a brand name and not indicitive of their function as they are the same. Basically they are just a long nut with an internal set screw to hold the adjustment. They are definitely superior to the original jam nuts when using solid lifter camshafts. The Boss 302 engine uses a smaller jam nut on top of the regular jam nut to more positively lock the adjustment.
-Fred-