The W3C DOM specifies a way of treating a document as a tree of nodes. In this model, every discrete data item is a node, and child elements or enclosed text become subnodes. Treating a document as a tree of nodes is one good way of handling XML documents (although there are others, as we'll see when we start working with Java) because it makes it relatively easy to explicitly state which elements contain which other elements; the contained elements become subnodes of the container nodes. Everything in a document becomes a node in this model—elements, element attributes, text, and so on. Here are the possible node types in the W3C DOM:

  • Element

  • Attribute

  • Text

  • CDATA section

  • Entity reference

  • Entity

  • Processing instruction

  • Comment

  • Document

  • Document ...

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