A hatch is an entity that represents an area filled with a pattern or gradient
that is bounded by a closed planar contour created from planar entities with
which it is associated. Engineers use hatches for sectioning arrangements in
drawings, for the texture of materials, and for gradient fields.
A sample project of working with hatches is located in the Drawing\Examples\DevGuide\OdHatchEx
subdirectory of the ODA installation folder (for example, C:\Program Files\Open
Design Alliance).