ACUCOBOL-GT includes a number of definition files. These files make it easier to use some of ACUCOBOL-GT's special features, such as graphical controls, color configuration, and Windows HELP. Many of the definition files contain predefined data structures for use with ACUCOBOL-GT runtime routines. You can include these structures easily in your program by COPYing the definition file into your program. All of the definition files have the three character ".def" extension in their name. Most reside in the "sample/def" subdirectory of your ACUCOBOL-GT directory. How and when to use these files are documented with the feature or function that the file supports (such as with a runtime library routine or in Special Names section).