If the http://db.kreie.net URL doesn't work, go to this website to access the scripts and other files used in this video series. https://sites.google.com/view/db-krei...
APEX 18.1 video 22 of 30: Create page groups. Organize the application pages by assigning them to a page group. Create forms for lookup/reference tables and put them in the “maintenance” page group. Review the data model and the progress made in the web application.