XML.XMLDecl
The XML Declaration is represented in the message tree by a syntax element with field type 'XML.XMLDecl'.
If the XML declaration is created by the XMLNS parser its
name is ‘XMLDecl'. However, when a message tree is being written,
the name is not important; only the field type is used by the parser.
The following shows an example of a declaration:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE s1 PUBLIC "http://www.ibm.com/example.dtd" "example.dtd">
<s1>........</s1>