The problem with trees Many systems are organized hierarchically. The CERNDOC documentation system is an example, as is the Unix file system, and the VMS/HELP system. A tree has the practical advantage of giving every node a unique name. However, it does not allow the system to model the real world. For example, in a hierarchical HELP system such as VMS/HELP, one often gets to a lead on a tree such as: HELP COMPILER SOURCE_FORMAT PRAGMAS DEFAULTS only to find a reference to another leaf: Please see HELP COMPILER COMMAND OPTIONS DEFAULTS PRAGMAS and it is necessary to leave the system and re-enter it. What was needed was a link from one node to another, because in this case the information was not naturally organized into a tree. Tim Berners-Lee, Seeing With Fresh Eyes A City Is Not a Tree hierarchywww
Cool URIs don't change An Essay by Tim Berners-Lee www.w3.org What makes a cool URI? A cool URI is one which does not change. What sorts of URI change? URIs don't change: people change them. The User Interface of URLs www
Scenes of thoroughgoing sameness In places stamped with the monotony and repetition of sameness you move, but in moving you seem to have gotten nowhere. North is the same as south, or east as west. Sometimes north, south, east and west are all alike, as they are when you stand within the grounds of a large project. It takes differences—many differences—cropping up in different directions to keep us oriented. Scenes of thoroughgoing sameness lack these natural announcements of direction and movement, or are scantly furnished with them, and so they are deeply confusing. This is a kind of chaos. Jane Jacobs, The Death and Life of Great American Cities The Image of the CityThe Great Blight of Dullness confusionchaos