notation for probability distribution (double absolute)

Question

I am trying to understand this term in an equation, but I am somehow confused. Can someone clear it for me ?

$KL(q_2(z_2|x_2)||p_{\eta}(z))$

Answer 1

Kullback-Leibler divergence between the distribution $q_2$ of $z_2$ given $x_2$, and the distribution $p_\eta$ of $z$