How to access NS nodes

[Christian Geuer-Pollmann]

Hi,

How can I access all visible namespaces for a particular Element in DOM?

<A xmlns:a="a-ns"><B xmlns:b="b-ns"><C /></B></A>

If I have the 'C' Element, how do I get a list which contains the 'a' and 
'b' namespace desclarations, which are in scope?