Configuration energies in ligand field calculations

Dear developers,

I have two simple questions (hopefully) about ligand field calculations with Quanty.

Firstly I don't understand what is the origin of the $U_{dd}$ in the second equation below (this is a comment section from the XAS L2,3 calculation with ligand field).

-- The $L^{10} d^n$ configuration has an energy 0

-- The $L^9 d^{n+1}$ configuration has an energy $\Delta$

-- The $L^8 d^{n+2}$ configuration has an energy $2*\Delta+U_{dd}$

Secondly, in the final state of core photoemission calculations the energy of which electronic configuration is set to zero? Is it the $p^5 d^n$ configuration or another? Why?

All the best, Hélène