Trying to understand Mat::dot and 2d matrices, in OpenCV

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Here is my code:

  uchar a[2][4] = {1,2,3,4,5,6,7,8};
  Mat b = Mat(2,4, 0, a);

  uchar c[2][4] = {1,2,3,4,5,6,7,8};
  Mat d = Mat(2,4, 0, c);

  cout<< b.dot(d);

The output is 204. Can someone show me presicly which elements have the dot product computed, and when. I didn't understand when the Documentation said "If the matrices are not single-column or single-row vectors, the top-to-bottom left-to-right scan ordering is used to treat them as 1D vectors."