Enigma operators also had a tendency to choose predictable letter combinations as indicators, such as girlfriends' initials or a pattern of keys that they saw on the Enigma keyboard. These became known to the allies as "Cillies" ("Sillies" misspelled). Using the data thus gained from the study of cycles and the use of predictable indicators, Rejewski was able to deduce six permutations corresponding to the encipherment at six consecutive positions of the Enigma machine. These permutations could be described by six equations with various unknowns, representing the wiring within the entry drum, rotors, reflector, and plugboard.