  We establish conditions under which the experimental verification of quantum
error-correcting behavior against a linear set of error operators $\ce$
suffices for the verification of noiseless subsystems of an error algebra $\ca$
contained in $\ce$. From a practical standpoint, our results imply that the
verification of a noiseless subsystem need not require the explicit
verification of noiseless behavior for all possible initial states of the
syndrome subsystem.

Quantum Physics