Hi Folks, Inside our brain information is in parse trees: The parse trees are structured according to a grammar, such as the English grammar. When I want to communicate information to you I linearize the parse tree and transmit the linearization (i.e., the sentence) to you. You receive the sentence and immediately reconstruct the parse tree and apply semantics to the parse tree: So information is exchanged by linearizing a parse tree, transmitting the sentence, and at the receiving end reconstructing the parse tree. This is true for humans as well as for web services: A web service has information in a DOM (parse) tree, it linearizes (serializes) the DOM tree into an XML string, transmits the XML string, and the receiving web service reconstructs the parse tree and then applies semantics to it: Neat! /Roger