Hi @andrewfullard ,

I’m working on issue #409 to clean up how J values are handled in CMFGEN data. Currently, in the cross_sections_squeeze function (carsus/io/cmfgen.py), J values are removed from ion_levels["label"] with the following code:

python

if ion_levels["label"].str.contains(r"\[").any():
    # Remove the "[J]" term from J-splitted levels labels
    ion_levels["label"] = ion_levels["label"].str.rstrip("]")

    # Drop the [J] term completely to avoid shape mismatch. Something to perhaps store in the future
    ion_levels["label"] = ion_levels["label"].str.split("[", expand=True)[0]
However, J values are not stored anywhere.

I have a few questions regarding how to proceed:

1. Where should J values be stored? Should I add a new "J" column in ion_levels, or should they be integrated into level_number?
2. How should J values be stored? As integers/floats or as strings?
3. Where is ion_levels originally created? I need to modify it to store J values but want to confirm the correct file and function.

Looking forward to your guidance!

1. A column in ion_levels isn't really possible because of the shape mismatch issue. A separate dataframe may be needed
2. Integer
3. You will need to go looking through the code to find out. It is probably in the CMFGEN data reader.