Configuration-average rates and unresolved transition array theory are comb
ined to calculate non-local thermodynamical equilibrium (NLTE) spectral pro
perties of plasmas. This approach turns out to be very efficient for NLTE p
lasmas involving complex ions such as mid-Z plasmas. Explicit expressions a
re given for all the needed configuration-average collisional and radiative
rates involved in population kinetics calculations. This approach is used
to calculate the x-ray spectral emission of an L-shell ionized germanium pl
asma.