This rule is applicable when a row or column has one remaining water square left to find, and the remaining non-water squares are connected. The end squares of the connected sequence cannot be water, as this would force a ship exceeding the largest ship size.
In the example above, the row has a tally of five. Since four water squares have been found, there is one remaining water square to locate.
There are six non-water squares in a connected sequence: (I,5) to (I,10). The square (I,5) cannot be the last remaining water, as this would force a ship of length five in (I,6) to (I,10). Likewise, (I,10) cannot be water. This allows us to finalize the end squares as segment wildcards.