To be or not to be : CTO - The very obvious ones 01 c

The Greek drama continues, altough not in Greece, but in the former Eastern Germany.
Loads of stamps were put in the market, and were sent into the world and the albums of collectors.
Rarely you 'll fine one of those stamps really postally used.

The stamps are all real, and luckily, some catalogues mention the usage of CTO cancels.
Normally a CTO cancelled stamp is worth less then half of the catalogue prices, or postally used stamps are more valuable then the prices mentionned in the catalogues.
Other cancels for philatelistic reasons, will be shown later on.

⊙ symbol for cancelled stamps
◍ symbol for CTO cancelled stamps

Another (more friendly) way to describe CTO's is : cancellations for philatelistic usage, but CPU sounded too much like computer processing unit, doesn't it?