In Hypertext: From Text to Expertext, Rada proposes to classify hypertext according to scale: "Small-value hypertext or microtext is a single document with explicit links among its components" (22). These are the systems which we have called document hypertexts. At the other end of the scale, "[l]arge-value hypertext or macrotext emphasizes the links that exist among many documents rather than within one document" (68). The pre-eminent example of a macrotext is Xanadu.