“A few interfaces to traversing a space are the standard Windows GUI, a Nokia mobile telephone menu system, a text adventure, DOS. Put aside what the entire map looks like and how it’s presented on the screen — whether it’s a network or a hierarchy. Put aside how the memory of navigation is presented, other windows open in the background, or a numerical crumbtrail in the corner. What remains? What remains is for each node there are a number of exits and a number of items attached to it.”