RDF tutorial / reference that was on XULPlanet

Hello,

I'm looking for tutorial (or reference ) that was on XULplanet.com. I 
remember there was good document that described how to manipulate RDF 
datasource, what are difference between various RDF functions like 
GetTarget, HasAssertion, etc.; a lot of examples.
There also was a table, comparing these functions and their parameters.
Today, find something on developer.mozilla.org is big challenge.

Thanks for any help,

Alex.