query regarding the reference model

Hi, for the task of `imdb_text_continuation`, I looked into the config file `gpt2_ppo_on_supervised.yml` where `policy` contains `model_name: rajkumarrrk/gpt2-fine-tuned-on-imdb-positive-reviews`. This is the model that will be improved but which is the `reference` model?
I want to provide the checkpoints for both the `reference model` and the model that I want to improve i.e. `policy model`. In fact, they are the same models.