[hn92726819]

Thanks for the correction! It seems more complicated after looking more into it.

According to https://en.m.wikipedia.org/wiki/Filename , reserved characters are:

HFS:

> :

HFS+:

> : on disk, in classic Mac OS, and at the Carbon layer in macOS; / at the Unix layer in macOS

APFS:

> In the Finder, filenames containing / can be created, but / is stored as a colon (:) in the filesystem, and is shown as such on the command line. Filenames containing : created from the command line are shown with / instead of : in the Finder, so that it is impossible to create a file that the Finder shows as having a : in its filename.

TIL about a 'carbon layer' and 'POSIX layer'