C# Definition:

    [ComImport, Guid("0000010b-0000-0000-C000-000000000046"),
    InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IPersistFile: IPersist
    {
        new void GetClassID(out Guid pClassID);
        [PreserveSig]
        int IsDirty();

        [PreserveSig]
        void Load([In, MarshalAs(UnmanagedType.LPWStr)]
            string pszFileName, uint dwMode);

        [PreserveSig]
        void Save([In, MarshalAs(UnmanagedType.LPWStr)] string pszFileName,
            [In,MarshalAs(UnmanagedType.Bool)] bool fRemember);

        [PreserveSig]
        void SaveCompleted([In, MarshalAs(UnmanagedType.LPWStr)] string pszFileName);

        [PreserveSig]
        void GetCurFile([In, MarshalAs(UnmanagedType.LPWStr)] string ppszFileName);        
    }