Hypertext Components: Change Tracking Text Editor
This simple text editor tracks all changes, so each stage in the development of a text and its entire history can be reconstructed, be it for version/revision control, branching off multiple versions, diffs or collaborative editing. Undo/redo (alias back/forward) and working with ranges of selected text not supported yet, but navigation keys like arrow keys, Home, End, Delete, Page Up/Down. The editor or at least the method/principle could be part of a hypertext system very different from the web, where the latter is more an application interface and the former geared towards mostly static text, an environment for the text worker, who writes, annotates, marks up, analyzes, transforms and curates the knowledge of the world, in an open and ethical way.
Update: Found the short mention of the idea by Ted Nelson I was referring to. It's in https://www.youtube.com/watch?v=ohiKTVVtDJA#t=8m42s from 8:42.