The decc$translate_vms function translates the given OpenVMS file
    specification into the equivalent UNIX style file specification,
    whether or not the file exists. The translated name string is
    stored in a thread-specific memory, which is overwritten by each
    call to decc$translate_vms from the same thread.

    This function differs from the decc$from_vms function, which does
    the conversion for existing files only.