I know that giving short, clear URI that do not change with time is considered good manners, but I need to create a system that is designed not to have them. But to do this I need to go back and find the document in which first it was explained that there should be a single URI per resource. And that it should not change with time. It is probably a document from T.B.L. or from the w3c. Anyone knows which document would that be?