per pale

The background of the shield can be divided into two potrtions in a variety of ways, and each portion treated differently. In the heraldry of continental Europe there is a tendency to use these areas to combine two different designs, but in British and Scottish heraldry the preference is to treat the divided field as a single decorative element with other features placed as normal. Whatever tradition is followed, one of the most common divisions is per pale, a simple separation along a vertical line. Wade assigns no particular meaning to the use of this division, but suggests that they simply arose from the multi-coloured garments typically worn at the time of the birth of heraldry. The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P56