Computer Networking: A Top-Down Approach, 7/e

This figure uses three different charts to illustrate two-dimensional parity. In the first chart, a blue arrow points from left to right at the top, and is labeled "Row parity. A blue arrow points from top to bottom on the left, and is labeled "Column parity." The chart can be viewed in rows or columns, and appears like this:

d_1,1 ... d_{1, j}

d_2,1 ... d_2,

... ... ...

d_i,1 ... d_{i, j}

d_{1, j+1}

d_{2, j+1}

...

d_{i, j+1}

d_i+1,1 ... d_i+1,j

d_{i+1, j+1}

The second chart is titled "No errors" and appears like this:

1 0 1 0 1

1 1 1 1 0

0 1 1 1 0

0 0 1 0 1

The third chart is titled "Correctable single-bit error." It is the same as the previous chart, except a blue arrow points from top to bottom through the second column from the left, to a point labeled "Parity error," and a second blue arrow points from left to right through the second row down from the top, also to a point labeled "Parity error."