This allows you to determine how highly Nimzo values the strategic advantage of the Bishop pair. With lower settings, you'll see Nimzo more readily accept the trade of a Knight for a Bishop. Influences the time control. For each move in the movelist in addition to this number of moves some additional time is allocated. So with lower values more time is used in the middlegame.
Higher values tend to slow down the program, which can be critical in blitz games.
This function allows you to trade off some endgame knowledge for increased search speed. See ETN for Sept. 27, 1998. Note that these settings usually interact with each other, making it entertaining to see how the alteration of one setting can have an effect on the others. I'm looking forward to diving in and tweaking Nimzo7.32 in myraid ways. With some judicious tweaks, I can already see how Nimzo7.32 will be like having my very own chess club on my computer.