Let M be a model of ZFAC (ZFC modified to allow a set of atoms),
and let N be an inner model with the same set of atoms and the same pure sets (sets with no atoms in their transitive closure) as M. We show that N is a permutation submodel of M if and only if
N satisfies the principle SVC (Small Violations of Choice),
a weak form of the axiom of choice which says that in some sense,
all violations of choice are localized in a set. A special case is considered in which there exists an SVC witness which satisfies a certain homogeneity
condition.