I have the following questions I can't answer by myself: What is the version of XML one should use? 1.0 or 1.1? Wierdly, 1.0 seems to be more updated and more used than 1.1... how is this possible? Is the prolog <?xml version="1.0"> necessary in an XML document? If not, is there a default version (1.0 or whatever) that the processor assumes when the prolog is not present?