This approach can be a form of "content filtering" or "content segmentation," where the site only retrieves and shows content relevant to the user's current focus or selection. It can help reduce load times and improve user experience by presenting only the most relevant information, rather than overwhelming users with a full table of contents upfront.

So when a user clicks one of the KB categories in the portal, only the articles of that section are loaded, rather than the entire table of contents.