2.2 Infosets 39
Figure 2.4 XML data model for a typical Medline citation. Element nodes are shown
using rectangles, text nodes are shown using ovals, child links are unlabeled, and
attributes are labeled with the attribute name.
The formal semantics of XML documents is concerned with whether two
infoset models are the same. The most obvious requirement for two infosets
to be the same is that the nodes and links correspond with one another. The
more subtle requirement is concerned with the arrangement of the nodes.
For two infosets to be the same, the children of each node must be in the
same order. For example, suppose that the two first two child elements of
the Medline citation were reversed as follows: