One of: element, attribute, text, cdata, comment, chunk
and (EXPERIMENTALLY!) entity_reference. A
chunk is a character string which forms a well-balanced
peace of XML.
Example 1.
add element hobbit into //middle-earth/creatures;
add attribute 'name="Bilbo"' into //middle-earth/creatures/hobbit[last()];
add chunk '<hobbit name="Frodo">A small guy from <place>Shire</place>.</hobbit>'
into //middle-earth/creatures;