Traversing Problem (XPath)

Here is the "tree" I am trying to traverse:

<thead>
    <row>
        <entry></entry>
    </row>
</thead>
<tbody>
    <row>
        <entry>

My context node is tbody/row/entry and I want to test for a value in
thead/row/entry but I can't figure the path.

example:  <xsl:when test="start-with(????,'value')">

What path can replace ???? and get me to the header row entry?

Appreciate any help.

Ken Roberts
San Antonio, TX