Electronic Journal
A common requirement is for the application to display on the screen an 'electronic journal' which is formatted by using the printing facilities of the DP4 Terminal Manager and OSDI but which is displayed using the output functions (such as map_draw() and show_c()) and which can be scrolled by pressing cursor keys.
A possible way to implement this would be for the application to print to an electronic journal POD implemented in the OSDI, which stores its output in a file; when this is to be displayed on the screen, the application selects input from an electronic journal input device which then echoes the file contents back to an input field in the appropriate place on the screen.