More on using RDF Forms to maintain application state in machine to machine services: If RDF forms contained RDQL to constrain parameters, then the client would know more completely how to fill in the "form". Say the form required submitting two flight numbers: departure and return. Both have rdf:type FlightNumber, but you better put the right one in the right field. A little RDQL, drawing on terms from the service's ontology, could constrain the destination city of the departure flight to be the same as the origination city of the return flight.