GatorBoxes (an AppleTalk<=>Ethernet Apple File Sharing / NFS bridge) would let Mac users create files in the Unix file system with slashes in their names (presumably because of NFS shenanigans going on in the kernel).
Macs let you use "/" in file names, but instead used ":" as the path separation character.
It seemed to work fine and dandy at the time, until you ran "restore" and discovered your backups were corrupted!
Just for fun: guess what happens when you create a Mac file name with a slash in it today?
It works!
Or it seems to work. But behind the scenes, the Finder and Mac user interface libraries actually convert the "/" to a ":", which you can see with "ls". But at least it doesn't corrupt your backups!
Classic MacOS used : for the directory separator, so you could freely put / in your filenames. Modern macOS converts / in the UI to : under the hood in order to retain compatibility, while banning : in the UI (the same restriction that classic MacOS had).
Macs let you use "/" in file names, but instead used ":" as the path separation character.
It seemed to work fine and dandy at the time, until you ran "restore" and discovered your backups were corrupted!
https://en.wikipedia.org/wiki/GatorBox
https://news.ycombinator.com/item?id=20007875
Just for fun: guess what happens when you create a Mac file name with a slash in it today?
It works!
Or it seems to work. But behind the scenes, the Finder and Mac user interface libraries actually convert the "/" to a ":", which you can see with "ls". But at least it doesn't corrupt your backups!