  While the formal valence and charge state concepts have been tremendously
important in materials physics and chemistry, their very loose connection to
actual charge leads to uncertainties in modeling behavior and interpreting
data. We point out, taking several transition metal oxides (La$_2$VCuO$_6$,
YNiO$_3$, CaFeO$_3$, AgNiO$_2$, V$_4$O$_7$) as examples, that while dividing
the crystal charge into atomic contributions is an ill-posed activity, the 3d
occupation of a cation (and more particularly, differences) is readily
available in first principles calculations. We discuss these examples, which
include distinct charge states and charge-order (or disproportionation)
systems, where different "charge states" of cations have identical 3d orbital
occupation. Implications for theoretical modeling of such charge states and
charge-ordering mechanisms are discussed.
