  Information-theoretical restrictions on the information transfer in quantum
measurements are studied. They are derived for the measurement of system S by
detector D, registrated and processed by information system O. The formalism of
inference maps in Hilbert space is used for it; it permit to calculate O
restricted state which contains available for O information on S parameters.
It's shown that the principal information losses, inevitable in this formalism
and induced by Heisenberg commutation relations, stipulate the stochasticity of
measurement outcomes, registrated by O in the individual events.
