INT 2F U - IFSFUNC.EXE (DOS 4.x only) - ???
        AX = 112Fh
        SS = DOS DS
        STACK: WORD function in low byte
                00h ???
                    DS:SI -> Current Directory Structure???
                    CL = drive (1=A:)
                01h ???
                    DS:SI -> ???
                    CL = file handle???
                02h ???
                    DS:SI -> Current Directory Structure???
                    DI = ???
                    CX = drive (1=A:)
        ???
Return: CF set on error
            AX = DOS error code (see INT 21/AH=59h)
        CF clear if successful
Note:   called by DOS 4.0 kernel