Molecular Representation in "Learn Good Molecules"

Hello everyone,


I have been using the "Learn Good Molecules" to build a model that I then analyzed using the "View Top N Good and Bad Features". The latter component produces images of molecular fragments with some atoms replaced by stars.


Does anyone know what the stars that have replaced an atom mean? I thought they were variable atoms present in the training set, but that interpretation does not make sense for the chemistry we are considering.


Thanks!


Agis