Rejewski would now know that indicators with the pattern "..E..E" were from a message key of "..Z"; similarly an indicator of "..Z..Z" were from a message key of "..E". In the day's traffic, he might find indicators such as "PKZJXZ" or "RYZOLZ"; might one of these indicators be the common (lazy) message key "EEE"? The characteristic limits the number of possible permutations to a small number, and that allows some simple checks. "PKZJXZ" cannot be "EEE" because it requires "K" and "E" to interchange in "B", but both "K" and "E" are part of the same cycle in "BE": (kxtcoigweh). Interchanging letters must come from distinct cycles of the same length. The repeating key could also be confirmed because it could uncover other repeating keys.