From the article: "Iterator is a behavioral pattern used to access the elements of an aggregate sequentially,
without exposing the aggregate's underlying representation. It is particularly useful when you want to
encapsulate special logic for the traversal of a structure like a DOM tree."
This pattern by Fabio Arciniegas is presented in the January 2000 article Design Patterns in XML Applications on XML.com.
This pattern takes the original Gang of Four Iterator pattern and places it into an XML processing context.