Markus, in answer to your question:
(1) Should we merge Relations with Attributes by providing a new datatype, and
by treating untyped attributes as relations by default (instead of rejecting
them as done now)? Why?/Why not?
(2) If only one remains, should we rather use the syntax "::" or ":=" for
annotations? The syntax ":=" suggests a way of writing inverse relations in
queries via "=:", but maybe this is not obvious enough to be a good idea.
Which syntax looks more user-friendly in general?
(3) Should we call the remaining semantic elements "Relations"
(4) How would the type "wikipage" that is used for emulating relations beI think 'wikipage' is clear, but not elegant. Another option is to have the type be "relation". (In this case the semantic elements would need to be called 'attributes', and one type of attribute is a "relation". It fuzzies the terminology of entity relationship modeling, but it could work). "link" is also a good choice.
called? "Article", "Page", "Wikipage", "Link", ...?