> <\body> Having written a working interface between your system and , you may want to improve it further. Below we will discuss a few directions for possible improvement. First of all, you may want to customize the keyboard behavior inside a -session and add appropriate menus. The procedure for doing that is described in the chapter about the extension language and you may add such support to the file . We again recommend you to take a look at the plugins which are shipped with inside the directory . Certain output from your system might require special markup. For instance, assume that you want to associate an invisible type to each subexpression in the output. Then you may create a macro with two arguments in and send expressions like to during the output. In case you connected your system to using pipes, you may directly execute commands during the output from your system by incorporating pieces of code of the form: <\indent> <\verbatim> [DATA_BEGIN]command:scheme-program[DATA_END] in your output. Inversely, when the cursor is inside a session of your system, you may use the command: <\indent> in order to execute a command of your system. >