Why is the ```lbcode``` test needed?
As far as as I can make out, LBCODE relates specifically to the 2d coordinate dimensions aka the 'x' and 'y' of the field.
When len(LBCODE)==5 you have a cross-section, and the 'x' or 'y' could be a vertical type coordinate, but I don't see that this affects the interpretation of LBLEV ?

For reference, I see that the existing 'depth' case (lbvc==2) test also contains an identical ```len(f.lbcode) != 5``` clause.  However, the  'pressure' case (lbvc==8) does not.

If anyone knows why this is "right" I'd appreciate it as I'm just now trying to write something similar myself.