Vienna Gambit
w
    a
        b
        c
        d
        e
        f
        g
        h
    8
      8
    7
      7
    6
      6
    5
      5
    4
      4
    3
      3
    2
      2
    1
      1
    a
        b
        c
        d
        e
        f
        g
        h
    b
    Black replies with the mirror image 1...e5, the most popular reply at all levels.