[XML4Lib] needed: 1 xpath expression

[Eric Lease Morgan]

Needed: 1 XPath expression

Given the following XML snippet, how can I extract the value of the  
100 field, subfield a:

<find-doc>
  <record>
   <metadata>
    <oai_marc>
     <varfield id="090" i1="" i2="">
      <subfield label="a">ND497.H678</subfield>
      <subfield label="b">M786</subfield>
     </varfield>
     <varfield id="100" i1="1" i2="0">
      <subfield label="a">Moore, Robert Etheridge,</subfield>
      <subfield label="d">1920-</subfield>
     </varfield>
     <varfield id="245" i1="1" i2="0">
      <subfield label="a">Hogarth's literary relationships.</subfield>
     </varfield>
    </oai_marc>
   </metadata>
  </record>
</find-doc>

I'd be willing to bet there is a one-liner lurking somewhere here.

-- 
Eric Lease Morgan
Hesburgh Libraries, University of Notre Dame

(574) 631-8604