  It will be shown that the Peres-Mermin square admits value-definite
noncontextual hidden-variable models if the observables associated with the
operators can be measured only sequentially but not simultaneously. Namely,
sequential measurements allow for noncontextual models in which hidden states
update between consecutive measurements. Two recent experiments realizing the
Peres-Mermin square by sequential measurements will also be analyzed along with
other hidden-variable models accounting for these experiments.
