StretchText, generally attributed to Ted Nelson, is a form of hypertext in which links, or summary snippets, can be expanded in place: in other words, you can “stretch” parts of the text that you want to see in more detail to zoom in on them. Implement stretch-text in TiddlyWiki using a template or procedure that allows you to expand and contract a tiddler serving as the “next level down”.

You can find an example and a TiddlyWiki implementation as the TiddlyStretch plugin in my list of cynical laws.