John was strolling down the beach when he spotted a glass bottle washed ashore. Curious, he picked it up and saw that it was empty but for a piece of paper with some typed message. When he looked closer at the message, he was disappointed. It wasn’t in English. It looked Russian. Luckily, he had a Russian-speaking friend. “It is not Russian,” the friend said, “but Ukrainian. I think I can manage to make sense of it”. The message was from the magazine “National Geographic World”, part of a study to map out ocean currents, and had instructions on where to send information about where and when the bottle was found.
Three distinct phases can be discerned in going from spotting the bottle on the beach to understanding the message, and failure in any of those stages would lead to not understanding the message.
I here use the terminology from Douglas Hofstadter’s “Gödel, Escher, Bach”, where he uses the three terms Frame message, outer message, and inner message.