If you have:

<xsl:template match="A">
<z>
  <a>
  <b>
  <c>
  <xsl:variable name="x"/>
  <d/>
  <e><f/></e>
  <g/>
</z>
</xsl:template>

then the places where variable x is visible are the instructions d, e,
f, and g: that is, the following siblings of the xsl:variable element,
and their descendants.

Michael Kay