Question about news shock horizons

Dear all, I have a question about the horizen about news shock , “mu_r = rho_r * mu_r(-1) + eps_r_surp + eps_r_antic(-4)”,in this expression, “eps_r_antic(-4)” means a single horizon or multiple horizons?
I don’t know how to distinguish expression of a single horizon and multiple horizons about news shock. Can anyone help me?And give an example if possible.

I am not sure I understand. eps_r_antic(-4) means a four period anticipated news shock. I would say that is a single horizon.

Thanks jpfeifer, I think I understand.