A method is presented of operating on signatures from a cycling register such that the complexity of identifying multiple failing tests is comparable to that of identifying a single failing test. The method has some interesting aliasing characteristics. The authors show the probability of aliasing and suggest how it can be kept relatively small. The efficiency of the method decreases as the number of failing tests increase. The reduction in efficiency is due to an increase in aliasing probability caused by footprints being lost in the cycling registers. The larger the number of failing tests, the greater is the chance that aliasing will occur.