4D 2003 introduced a set of XML commands that allowed crawling the "DOM" tree of an XML document. To find a specific element in that version, you would have to write your own method that went through the XML reference nodes one by one.
In 2004, a new command named DOM Find XML element allows you to search for a specific node in the document using XPath. For example, suppose you had a document like the following:
Using the new command, you can easily locate the "b" element:
$a:=DOM Parse XML source("my.xml")
$b:=DOM Find XML element($a;"/a/b")
Likewise, to locate the "e" element from element "a," you would use the following:
$e:=DOM Find XML element($a;"/a/b/c/e")
Or you could locate it from the "b" element:
$e:=DOM Find XML element($b;"/b/c/e")
As you can see, it is much simpler to use this one command as opposed to looping through the document manually looking for a specific element.