Ken Manheimer has also posted a proposal (a little bit dated) about what he calls
Organization Objects, and a really good companion paper about the
motivations for organization objects. The motivations paper discusses how the parent/child and table of contents relationship(s) were done for ZWiki, and how Organization Objects (which bear similarity to
XLink) would have benefited the application.
A bullet point in the Organization Objects proposal that I really liked is:
- Living with only links and searches is like living in an
imaginary world where every room is connected to every other by
transporters - it lacks a basis for regionality, neighborhood.
In other words, it lacks progressively grouped regions by which you
can realize "where you are".