Use the rootElement element to identify the element declaration in the schema that is the Document element of the XML documents to be shredded. Most schemas contain many global element declarations (elements that are declared at the top level). Any of these elements can be the Document element (the top level element in the document tree). By specifying a root element, you establish the XML tree structure. For instance, if you are interested in shredding Purchase Order documents, you can specify the rootElement to be the PurchaseOrder element.