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Dispersion surface and absorption coefficients are calculated for the cases (000), (Ill), (ZOZ), and (311) of the four-beam diffraction assuming interaction of waves corresponding to (111) and (202) reflections. It is shown that the results of the calculations explain the basic features of the experimentally observed Borrmann effect in this case. PaCCYEITaHbI AHCIIepCEIOHHaH IIOBepXHOCTb I4 HO3@@EIuI4eHTbI IIOrJIOUeHBR RnH MODefi CTBEIX Me?HAy BOJTHaMM, OTpalrceHEIHM (1 11) EI (202). nOHa3aHO , YTO pe3yJIbTaTbI AaHHOrO paCYeTa O~WICHXIOT OCHOBHbIe OCO6eHHOCTH cnyqaeB (OOO), (in), (202) EI (3ii) YeTbIpeXBOJIHOBO~ nYr@naKum c Y Y~T O M ~3ak1-~K C I I~~H M~H T~J I L H O Ha6n~)AaeMOrO a @ @ e~~a EopMaHa ~n n 3~0 r o cnyqaH. COOTBeTCTByW~HMEI