 Chemical ordering and body-centering extinction

Sites at 000 and one half of each cubic coordinate give $F=f_A+(-1{)}^{h+k+l}{f}_B$. Identical sites produce a body-centered cubic lattice with absent odd-parity reflections. Distinct chemical species generally preserve only the simple cubic lattice translations, so those same odd reflections need not vanish. A geometric body center is not by itself a symmetry translation of the decorated crystal.