Regarding the concrete markup syntax, we have been experimenting with several DTDs prior to the current, still preliminary, version. The rationale for our current tags is as follows. Note that the Datalog DTD on the website is a bit more complex, but equivalent, to the one appended below. Downloading should work anyway. After some discussions, we found a set of tag names that sound reasonable to us.
Feedback is very welcome.
We'll need an explicit, abbreviating tag. Similarly, perhaps, for trigger rules and integrity constraints. This example rulebase contains four rules. The third and fourth rules are actually facts. The next rule is a fact that says, in English, that John sells XMLBible to Mary.