write_switch (lwrite)

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 ($\geq$ 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.