If the argument is
a non-zero integer, causes level populations and line emissivities in the interior of the
shell to be written to a fits dataset at each spatial step for later examination
or plotting. These files are named 'xout_detail.lis' and 'xout_detal2.lis',
and can become quite large
( 10 Mb) for a model with many spatial zones. Various fits
file manipulation routines can be used to filter and plot the
quantities in these files. Default value is 0.
New in version 2.5: if this parameter has a value -1 no fits output is produced.