The issue is when they are used in the SAME code, in the SAME place, to do the SAME thing. BTW, the 99999 is used in an IF that can NEVER be true in Crafty 19.x (which is what 1.6.1 copied). The -999999 is used in NextMove as a sort value for the hash move only, to push it to the bottom since it has already been searched. Not even sure that is a good idea any longer since the move itself is zeroed in the list anyway. I just try to not change things unless I am certain there is a point, in order to introduce fewer bugs that can be hard to find.