Ordinary outlines capture a rather simple relationship: something is at a level under, over, or the same as something else. By named and typed links, Tinderbox allows us to relate two notes according to an arbitrary relationship independent of the outline. But what if the outline structure itself captured several types of relationships?

IdeaGraph is an early work in progress that attempts just that. The kinds of relationships it has in mind are derived from the standard developed by the Semantic Web folks (RDF, the Resource Description Framework). The idea is that in the near future, we are going to want to structure documents so that the structure reflects their internal semantics. Right now, you can import a Web page into an outliner, but all you get is a collection of words. In the future, you should also be able to import (or create from scratch and display) the actual meaning of the site by semantics encoded in, or referenced by, that RDF.

The screenshot depicts this. The window on the right is like a cross between Tinderbox’s and Inspiration’s graphical views. Each note has a box. Each box can be linked to another by various relationships. But those relationships can be captured in an expanded notion of a tree structure. The left shows an outline that has this structure coded in symbols that in a regular Mac outliner would be triangles.