query for variable presence in a dataset

[Keith Lindsay <klindsay@xxxxxxxx>]

Hello,

Is there a way in ferret to determine if a variable is present or absent
in a dataset? I am building a journal script to automatically generate a
suite of plots from model output. However, sometimes diagnostic XYZ is
present and sometimes it is not. I'd like to have the journal script do
something like "if var_present(XYZ) then plot XYZ". Is this possible?

Thanks, Keith