A great advantage of hypertext is that you don't have to eliminate material in order to maintain the forward flow or to keep the text to a manageable size. Secondary or tangential things can be kept out of the main path but still accessible to the interested reader. However, there are some pitfalls here as well. The author has to develop more material which is not essential, and organize and classify it to make it convenient for the reader. The author furthermore has to maintain a credible level of detail throughout the text. If one area is developed with several layers of elaboration, why not another? If we create an expectation of "encylopedism", we have to either carry it through the entire text, creating a virtual universe, or set forth a self-evident set of criteria for things to be elaborated. For instance, presented with a clickable map of a medieval city, we might expect varying levels of detail based on the context. If a particular city was the focus, every building might be active, but the level of detail might not be terribly deep for any single one. If, say, the guild system were the focus, we would expect extensive elaboration on the different guild halls, as well as some treatment of the other important institution providing context. {Murray on encyclopedic simulations}