A survey of nonmagnetic band structures near the top of the 3d band is made. The aim is to combine these band structures with a wide variety of experimental data to determine the exchange splittings of the d bands ∆Edd and the s-p conduction band ∆Ess. Saturation magnetization, g factors, and high-field Hall data are analyzed and compared with the effect of s-d hybridization on the number of s electrons. One concludes that if the neck observed in magnetoresistance studies is associated with the same band edge as the Cu neck, ∆Edd<~0.8 eV. It appears that ∆Ess<~∆Edd2. Recent optical rotation data of Krinchik are interpreted as giving a direct measurement of ∆Edd. The value obtained is (0.6+/-0.1) eV, in good agreement with the values obtained from other data.