The *HIT section is optional if all 'line'
molecules are represented
by Look-Up Tables instead, but since you are
likely to have only one version of the HITRAN data then you might as well
keep the *HIT section in the driver table anyway (data available in
LUTs takes precedence).
The .par file is the 160-character record format that can be
downloaded from the HITRAN web-site.
Reading the .par file can be quite slow, so a faster alternative
is to convert the .par file to an RFM-specific binary format
(.hit file) using the