30 Input/output library [input.output]

30.10 File systems [filesystems]

30.10.2 Conformance [fs.conformance]

30.10.2.2 Operating system dependent behavior conformance [fs.conform.os]

Behavior that is specified as being operating system dependent is dependent upon the behavior and characteristics of an operating system.
The operating system an implementation is dependent upon is implementation-defined.
It is permissible for an implementation to be dependent upon an operating system emulator rather than the actual underlying operating system.