|Charts can be scheduled for a new edition for a variety of reasons. Some charts cover areas that are known to be constantly changing and always require a high number of chart corrections. In these areas, new chart editions may be printed once a year. On the other hand, some areas change very little so that charts covering those areas may have new editions printed once every five years. In some cases, the Coast Guard may request a new edition be printed in order to portray a new traffic scheme. New hydrographic surveys that change large depth areas on charts will often precipitate a new chart edition. Occasionally, NOAA may need to alter the printing schedule in order to address special circumstances.