* That there's never a \0 in a pathname
wchar names on MSWin UNICODE and WinCE. Symbian uses UTF16.
* That paths are seperated by /
Yes, Windows NT accepts /, VMS, VOS, RISC OS also, but MacOS classic had :, and VMS uses []. And there are still \ pathseps only, like DOS, OS/2, SYMBIAN, Novell NETWARE, AmigaOS4. Native Acorn RISC OS uses . as pathsep and : as in DOS.
Just the easiest ones.