Xanadoc
Xanadoc is one of the instantiations of the abstract concept of hyptertext documents envisioned by Ted Nelson in conjunction with his Project Xanadu. It makes use of World Wide Web technology (despite Nelson's general dislike of the Web for not implementing the superior hypertext ideas he had earlier), using URLs for addressing and with the current implementation being browser-based (though it is intended to become an open standard which can have many implementations on different platforms).
The basic structure of a document is in the form of an "EDL" file (Edit Decision List), consisting of a series of URLs pointing at the actual content (which, thus, must be already online) along with keywords indicating the type of linkage (which can be a transclusion of particular segments of a document into another, or a directed hyperlink at a specific spot of an article (shown in the user-interface of a viewer by a line pointing between two independently scrollable texts).
