Richard, what your book means by �a preamble�?
The closest official term I can think about is �prolog� = �XML declaration� + �DOCTYPE declaration�. Is it what the book mean? If XML document has a DTD (either external or internal), it has to be declared in <!DOCTYPE declaration
But it is also possible for an XML document not to have any accotiated DTD or Schema � then it doesn�t have <!DOCTYPE declaration (= preamble?)
Some ideas about Java&XML:
Processing XML with Java XML, Java, databases and the Web Java XML Application Categories