Simplifying, but Apple offered APIs using two path kinds: HFS uses colon as a path separator, POSIX uses slash. 25 years later, the HFS APIs are mostly dead. We just use POSIX.

I just wrote a file with a colon in the name and sent it to the iOS share sheet… which shows a slash.

I was going to convert both to hyphen/minus (the low ASCII one) out of paranoia anyway, plus 2026:03:25 is weird. I just wanted to see what would happen: I write POSIX, it shows HFS. Avoid both! #AppleDevelopment