  Relativistic calculations of the second- and third-order contributions in
magnetic field to the Zeeman splitting in boronlike ions are presented for the
wide range of nuclear charge numbers $Z=6$--$92$. The
interelectronic-interaction correction of the first order in $1/Z$ is evaluated
to all orders in $\alpha Z$. The higher-order corrections in $1/Z$ are taken
into account approximately by means of effective screening potentials. The
obtained results are important for interpretation of experimental data on the
Zeeman splitting in boronlike ions, in particular, for the ARTEMIS experiment
presently implemented at GSI.
