Here we describe the semantics that can be expressed in CL-Wiki, and the
syntax that will provide those semantics. This will lead to an abstract
design for the wiki.

Desired Semantics

We wish to clearly distinguish classes and individuals, and keep them
distinct from documents. Towards this end, we propose the wiki have
different namespaces for documents, classes, instances, and properties.

A document may or may not be semantically annotated. Any document that's
semantically annotated should have a primary class or individual (which we
shall together call a concept). Say the document has a link to another
target document. If the link is typed, and the target document also has a
primary concept, we can produce a triple corresponding to the link. This is
very similar to how links are described in semantic mediawiki, and a
variety of other wikis.

Where we differ is that we can introduce nested topics within a document at
any point. The outer topic must have a relation defined to the inner one,
thus again giving us a triple. Any links that occur within the scope of the
inner topic are related to that topic. However, topics with individuals as
their target cannot have any nested topics.

It is also possible to have a document without a primary topic, but with
topics declared within its scope. This implies that the document cannot act
as the target of a semantic link, but can produce triples nevertheless.

We thus have the following combinations of sources for the subject and
object of each triple. We can also have specific interpretations for each
of those combinations:

Subject | Object | Interpretation
--------+--------+------------------------------------------
Class   | Class  | Template slot with a type restriction
Class   | Ind.   | Template slot with a value
Ind.    | Class  | Own slot linked to an anonymous instance
Ind.    | Ind.   | Own slot with a direct value

Properties can either have literal values, or other concepts as values. The
nature of the property must be declared in its document. A property cannot
appear as a subtopic in any page. A page with a property as its primary
topic takes any other typed link as a direct value. This is essential to
support declaring the domain and range, for example.