  We consider quantum channels with two senders and one receiver. For an
arbitrary such channel, we give multi-letter characterizations of two different
two-dimensional capacity regions. The first region characterizes the rates at
which it is possible for one sender to send classical information while the
other sends quantum information. The second region gives the rates at which
each sender can send quantum information. We give an example of a channel for
which each region has a single-letter description, concluding with a
characterization of the rates at which each user can simultaneously send
classical and quantum information.
