This is Xpcn, an X-based development environment for programs written using the Program Composition Notation. To remove this window click the left mouse button in the close button at the bottom of the window. You are currently looking at the Xpcn top level. This window contains three parts. The top section of the window is the command window. By clicking the left mouse button on one of the commands, you can perform the action indicated by the button. The middle section indicates the current Xpcn directory. The bottom window gives a list of files in the current directory. Files are selected by pressing the left mouse button while the pointer is over the file name. If you want to change selections, just press the left mouse button over a different files or no file if you want to eliminate all selections. The directory window serves two purposes. If you selected a file in the directory window using the right mouse button and then select a command, the file will be used as an argument to the command. For example, if you select the file "foo.cnt" and then select the Gauge button, Gauge will be invoked on "foo.cnt". A file can be opened by double-clicking in the directory window. The action taked when opening a file depends on the type of file as determined by the filename extension. For example, if you double-click on a *.cnt file, Gauge will be invoked on the file. Double-clicking on a directory name opens that directory, thus allowing navigation of the directory system.