why do you add 4 states in the environement?

[greg2paris]

I went deeper in the code but their is something i cant understand.
In the file TFTraderEnv.py
I found this line inside the OhlcvEnv() class:
self.shape = (self.window_size, self.n_features+4)

I cant find those 4 features you add just before the training.
Where are they in the code?
Thank you for your awesome work.
greg