 Crossword grids elsewhere, such as in Britain, South Africa, India and Australia, have a lattice-like structure, with a higher percentage of shaded squares (around 25%), leaving about half the letters in an answer unchecked.For example, if the top row has an answer running all the way across, there will often be no across answers in the second row.Another tradition in puzzle design (in North America, India, and Britain particularly) is that the grid should have 180-degree rotational (also known as "radial") symmetry, so that its pattern appears the same if the paper is turned upside down.