XPath to structure information description

Hi,

In XML filters, you can set the description of structure information to be populated dynamically from a relative XPath. So far I'm having limited success with this, though.

This is my (simplified sample) XML:

<XML>
   <Item>
      <Number>000000000001234567</Number>
      <Name SID="XYZ">translatable text</Name>
   </Item>
</XML>

What I manage to do is fetch the SID with this XPath:

@SID

What I'm trying to do is fetch the Number. I have tried this two ways:

preceding-sibling::Number
../Number

But neither seems to work. So the question is, does the description have to be an attribute value of the translatable element itself, or is there a different approach to getting the description from another relative element?

Any pointers are much appreciated! Thanks!

Stephan