Again: Signing a ds:Object - what's the right XPath

Hi all,

let me ask again. What's the right XPath to completely identify a subtree 
based on the top-level element of the subtree. Using the XPath

here()/ancestor::ds:Signature[1]/ds:Object[1]

I can identify the first ds:Object in my ds:Signature. But for tor xpath 
ds:Transform to work properly, I have to modify this xpath that it doen't 
return a nodeset but evaluates to true for all descendant-or-self of this 
ds:Object. I tried

ancestor-or-self::node() =
here()/ancestor::ds:Signature[1]/ds:Object[1]

but this XPath fails to catch the Attributes inside e.g. the ds:Object. 
What mistake do I make?

Christian



> <ds:Signature>
> ...
> <ds:Transform Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
> <ds:XPath>
>  ancestor-or-self::node()
>            =
>  here()/ancestor::ds:Signature[1]/ds:Object[1]
> </ds:XPath>
> </ds:Transform>
> ...
> <ds:Object Id="object-1">some text</ds:Object>
> </ds:Signature>