Here is one hatch pattern definition from that file: This file can be opened and edited with a text editor that can handle ASCn files such as the Windows Notepad. The pattern definitions are contained in an external file named Acad. Unlike line types hatch patterns can not be created while you are in an AutoCAD file.
This section demonstrates the basic elements of pattern definition.
AutoCAD provides several predefined hatch patterns you can choose from (see Figure 20.9) but you can also create your own.