What is an extensibility element?

[relaxedrob]

Hi All!

I have been reading from this document in order to understand just
what an extensibility element is:
Web Services Description Language (WSDL) Version 2.0 Part 1: Core
Language
http://www.w3.org/TR/2004/WD-wsdl20-20040803/#eii-extensibility

So far I understand that it references an element in some namespace..
so that in a WSDL document I could have a binding like this:
<wsdl:input>
<soap:body parts="docToFormat" use="literal"/>
</wsdl:input>
which says the 'input' element consists (read extends) the docToFormat
element.

Is this about right?

Any advice would be most appreciated!

Rob