05 What ist the Base85 encoding?

https://en.wikipedia.org/wiki/Ascii85

Base85 is a group of different, mutually incompatible encoding methods that convert 8-bit binary data into a sequence of printable ASCII characters. They have in common that they encode blocks of four bytes each into five ASCII characters. This requires at least 85 different characters, which gave this method its name.

The most widespread use of this encoding is in the Postscript file format. This encoding version is also called Ascii85.