postix is the system used for ticket scanning and cash handling at Chaos Communication Congress and Chaos Communication Camp.
postix has been removed from GitHub for the time being because of a new law in Germany effective January 2020. The new § 146a AO introduces new requirements for cash register systems, such as integration of a certified signature device and specific export formats. These are not yet implemented by postix.
However, the law also makes it illegal to promote or share any software that provides cash register functionality but does not comply with the new regulations. We therefore needed to remove postix from GitHub to comply with this law. We do not yet know if this is temporary or permanent.