When items named in this function are found in the input data set (either 
data_set or idata_set), they are copied
into the simulated output.  Special items like evid or amt or
the like are not copied from the data set per se, but they are copied from
datarecord objects that are created during the simulation.
carry_out(x, ...)carry.out(x, ...)
model object
passed along
There is also a carry.out argument to mrgsim that can 
be set to accomplish the same thing as a call to carry_out in 
the pipeline.
carry.out and carry_out.  Using the underscore version is 
now preferred.