which the UQS is transmitted does not need to be proven to have a safe response. Only the signal generator and the strong link need to be proven to have safe behaviour until such time as the weak links render the weapon inert.. Critically for maintaining this safety, the strong link discriminator must be the only place in the entire system where "decisions" are made, and the transmission channel must never be permitted to retain knowledge of events, handle multiple events at once or re-order events. That may permit a single action to generate multiple signal events. Additionally, all events must be processed identically: to do otherwise constitutes pre-storage of knowledge of the UQS and biases the channel, Events may be sent or received in any format (e.g. digitally, as voltage levels, mechanically, etc) as long as these conditions were met; format translation is also permitted as long as the translators transmits each event before processing the next one. Unique signals were usually encoded as sequences of binary data (though strictly the data did not have to binary, it was deemed that the longer sequence was outweighed by the simpler implementations). Unique signals were carefully designed to have statistical properties extremely unlikely to exist unintentionally, and were also designed to be transmitted not only electrically via voltage or pulse-width modulation, but also mechanically (e.g. a push-pull rod), optically or pneumatically. Events are described alphabetically, rather than numerically (e.g. 0 and 1), to avoid confusion with specific physical signals; a two-event sequence would have "A" and "B" events. Examples of statistical weaknesses that undermine safety properties include sequence symmetry, periodicity, repeated events, imbalances between events (event-wise balance: almost equal numbers of "A" and "B" events), imbalances between pairs (pair-wise balance: "AA", "AB", "BA" and "BB" should be almost equal in occurrence) and correlations with other unique signals (as this would permit events from a different UQS to bias this one). Testing signals Testing and training signals that would ever be transmitted to a weapon were also carefully chosen to be statistically weak unique signals, which would still also test the integrity of the signal transmission system. This was done so that a test signal could never be mistaken for a genuine signal, which would have strong statistical properties. Thus the test signal would be very different and could never be mistaken for the valid UQS. In order to test the unique