  We extend the work by Appl and Camenzind (1988) for special relativistic
magnetohydrodynamic (MHD) jets, to fully general relativistic studies of the
standing shock formation for accreting MHD plasma in a rotating, stationary and
axisymmetric black hole magnetosphere. All the postshock physical quantities
are expressed in terms of the relativistic compression ratio, which can be
obtained in terms of preshock quantities. Then, the downstream state of a
shocked plasma is determined by the upstream state of the accreting plasma. In
this paper sample solutions are presented for slow magnetosonic shocks for
accreting flows in the equatorial plane. We find that some properties of the
slow magnetosonic shock for the rotating magnetosphere can behave like a fast
magnetosonic shock. In fact, it is confirmed that in the limit of weak gravity
for the upstream non-rotating accretion plasma where the magnetic field lines
are leading and rotating, our results are very similar to the fast magnetosonic
shock solution by Appl and Camenzind (1988). However, we find that the
situation becomes far more complicated due to the effects of strong gravity and
rotation, such as the frame dragging-effects. We show the tendency that the
large spin of the black hole makes the slow magnetosonic shock strong for the
accretion solutions with the same energy-flux.
