edit: i managed to fuck up the AVs for fighters but i hope you get the gist, will fix later
instead of having THAC0 values which you use by basically rolling d20 >= that number and adding the opponent's AC (a table is usually included to be helpful), whitehack works by giving each player a specific attack value (AV) to roll d20 <=. to account for AC, you also have to roll > whatever value is indicated for the opponent's armor. in a way, it's "THAC9". anyway i like it better than THAC0 and i wanted to see how it would work in b/x or OSE or whatever.
here is the table to convert from ose-style AC to whitehack-style AC.
here are the AVs for clerics and thieves:
for magic-users (why not 'mages'???):