Hatch patterns are commonly used in graphics software to highlight distinct areas of a map or drawing. There are three general techniques for filling in polygonal areas on a software canvas:
This page is dedicated to the discussion of the repeated vector pattern.
Official http://docs.autodesk.com/ACD/2010/ENU/AutoCAD%202010%20User%20documentation/index.html?url=WS73099cc142f4875513fb5cd10c4aa30d6b-7e57.htm,topicNumber=d0e368209%|%Documentation%|% from the Autodesk website for the popular commercial hatch definition format.