Stamp language, Babylonian confusion of tongues?
At the beginning of the last century, in a large number of countries, there was still a sometimes significant difference between the rate for a picture postcard and a letter postcard. Only a short greeting could be written on a picture postcard in order to be sent as printed matter. This prompted many, especially young people in love, to use the stamp to convey more than could be written down in words, by affixing the stamp in a specific way. This allowed them to avoid the postage costs for a letter postcard. This is how the language of stamps originated.
But is that language understandable to everyone? The intention was so: internationally applicable. Not much came of that! Not even in its own country. The stamp language was nowhere 'on paper'.
Click on the image to enlarge
Postcard printers jumped into this gap in the market and issued cards featuring the images of the stamp in various positions, along with the corresponding 'translation'. One printer gave the explanation for an upside-down affixed stamp as: My heart is no longer free. But what did the other printer say? 1000 kisses. Quite a difference.
The stamp pasted horizontally with the word Netherlands on the left meant: Be happy. But the other printer said: Do you love me? While a third printer meant: I am thinking of You. Whereas on a German card with the word Germany on the left it was declared: Write to me soon!


And what about the ZoP phenomenon (See under Stamp)!
http://people.zeelandnet.nl/acoomens/zop.htm