table indicating the lug settings for the drum might look like this: Bar 1 would have its lugs set in the "3" and "6" positions, bar 2's lugs in the "0" and "6" positions, and so on. Any lug in the "3" position, for example, will be pushed to the side by a guide arm when the currently active pin on key wheel 3 is in an "effective" position. Finally, the external key is set by rotating the key wheels to either a specific or random sequence of letters. In testing the internal key settings of the M-209, it is customary for the operator to set the key wheels to "AAAAAA", and proceed with encoding a message consisting of nothing but the letter "A." The resulting ciphertext is then compared with a long check string to verify that all of the internal settings have been performed properly. The check string for this particular configuration is: T N J U W A U Q T K C Z K N U T O T B C W A R M I O Key wheel pins come into play when they reach the lower part of the key wheel during rotation; it is here that they may contact or release the guide arm that deflects the lugs to the left. The active pin is offset by a particular amount from the letter currently being displayed on the front of the key wheel; when "AAAAAA" is showing on the key wheels, the pins that are in play are those associated with the letters "PONMLK", from left to right. Example encoding After the M-209 is configured according to the settings above, the machine is ready to encode. Continuing with the example of a known check string, the first letter to be encoded is "A". The operator sets the indicating disk to the letter "A", and turns the power handle. Since the key wheels are set to the string "AAAAAA", the active pins are "PONMLK"; according to the settings above, pin "P" is ineffective on the first key wheel, pin "O" is effective on the second key wheel, "N" is effective on the third, "M" is effective on the fourth, "L" is ineffective on the fifth, and "K" is effective on the sixth. The guide arms associated with effective pins will tilt forward and contact the rotating drum; in this case, guide arms 2, 3,