Pre-arranged signals are possibly amongst the most reliable but coded messages can probably be deployed effectively in situations where detainment is carried out through unsophisticated agents. Afew ideas:
- Word of mouth (properly reinforced) can be reliable at times;
- Signs in windows, especially shops where, for example, normal open/shut signs might be black and white but red, blue or other colours might indicate various conditions or circumstances. Trusted members of networks would be trained to recognise visual cues and spread the message accordingly;
- Semaphore along with morse code (which can be visual as well as auditory) are simple technologies that have fallen into disuse. As such they are potentially useful in clandestine communication;
- Letter boxing - like the window signs pre-arranged coloured paper or (eg.) 3 red lines on white background (even messages with lemon-juice??) slipped under doors, placed in letter boxes and other strategic places;
- Clothing with visual cues (not blatant but subtle) and blended with customs; and
- Smoke signals, signal fires and other signals like whistling, singing or playing particular instruments/tunes etc.
Just a few of a huge variety of ways to let people know what is going on. Depending on the circumstances of detention some of these approaches could be used to give messages of hope to detainees