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:  

   * flood with a single defined colour - currently this method is supported by the Tk canvas.
   * fill with tiled raster image (the wiki page discussing http://wiki.tcl.tk/1419%|%bitmap%|% indicates that this is possible in tk also) and 
   * fill with repeated vector pattern

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.

http://web.ncf.ca/fe361/hatch_geology.pdf%|%Examples%|% of hatch patterns, rendered with tcl and http://wiki.tcl.tk/13449%|%pdf4tcl%|%.

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