EDIT: I shouldn't have run to Wikipedia; much better explanation at scene.org (go figure): https://gotpapers.scene.org/?p=849 https://gotpapers.scene.org/?p=849

EDIT: I shouldn't have run to Wikipedia; much better explanation at scene.org (go figure): https://gotpapers.scene.org/?p=849 https://gotpapers.scene.org/?p=849 -- PLK = "PostLagerKarte", literally "mail storage card". It was (abolished 1991) a way to receive letters anonymously; like a P.O. box without your name attached to it. The [Wikipedia page](https://de.wikipedia.org/wiki/Postlagerkarte https://de.wikipedia.org/wiki/Postlagerkarte) even explicitly mentions its "illegal usage in the computing scene", so GP was likely referring to his friend using their P.O. box for (illegally) cracked software. Here's a shot at translating that Wikipedia paragraph: > Until their abolition, PLK cards were especially popular in the cracker scene because, compared to a regular P.O. box, no personal data had to be shared with the respective post office. PLKs were primarily used for anonymous sending and receiving of pirated software on floppy disks. [citation needed imho] The PLK addresses themselves were often listed digitally in the cracktros.