The element for the optional part has the name optionalpart.
It contains a list of elements for the entries in the optional part. These elements have the name pair. The pair elements have two attributes key and value.
The attribute key contains the key and the attribute value contains the value of the entry.
An example for the optional part:
<optionalpart> <pair key="copyright" value="GNU GPL 3"/> <pair key="type" value="the Berlin wall"/> </optionalpart>