Talked with Drummond this morning at iiw2007 . Finally getting to know the problem space that he is tackling. I have always been very vague on what he talks on Subject-predicate etc. and graph model etc.
Identifier usually is a pointer to an object and nothing more, but what he is trying to do is to build the relationship expression into the identifier itself.
To illustrate it, he was using
* has a
* is a
relationship. The example that he was drawing on was something like this.