Here's the problem I'm looking at: 

$F$ is a perverse sheaf (or a regular holonomic D-module, or even a mixed hodge module) on $\mathbb{C}^2$ stratified by $z_1 = 0$, $z_2=0$. It can be caracterized by a quiver
$$
  \begin{array}{ccc}
    \psi_{z_1}\psi_{z_2}(F) & \leftrightarrows & \psi_{z_1}\phi_{z_2}(F) \cr
    \uparrow \downarrow & & \uparrow \downarrow  \cr
    \phi_{z_1}\psi_{z_2}(F) & \leftrightarrows & \phi_{z_1}\phi_{z_2}(F)
  \end{array}
$$  
where arrows are the canonical and variation maps.


Consider $f(z_1,z_2) = z_1+z_2$ (or any curve passing through $(0,0)$ transverse to the axises). 

How can we compute 
$$
  can: \psi_f(F) \leftrightarrows \phi_f(F) : var
$$
in terms of these data?