// clist.pri

private:
    int  currPos;        // Subscript representing current position
                         //     (-1 if list is empty)
    int  lastPos;        // Subscript of last item in list
                         //     (-1 if list is empty)
    char data[LMAX_LENG]; // items in the list

    // CLASSINV:  -1 <= lastPos < LMAX_LENG
    //         && -1 <= currPos <= LMAX_LENG
    // ABSTRACTION MAP: the sequence of elements is data[0..lastPos],
    // and the cursor is currPos.