facet - associated fields

[Jae Joo]

Hi,
Can anyone help me how to facet and/or search for associated fields? -

<add>
 <doc>
  <field name="id">1234</field>
  <field name="headline">Baseball hall of Fame opens Jackie Robinson
exhibit</field>
  <field name="description">Description about the new JR hall of fame
exhibit.</field>
  <field name="pub_date">20071114</field>
  <field name="pubyyyymm">200711</field>
  <field name="price">0</field>
  <field name="news_type">press</field>

  <!-- subject 1 -->
  <field name="subject">Sports</field>
  <field name="subjectMatter">Baseball</field>
  <field name="subjectDetail">Major League Baseball</field>

  <!-- subject 2 -->
  <field name="subject">Arts and Culture</field>
  <field name="subjectMatter">Culture</field>
  <field name="subjectDetail">Heritage Sites</field>
 </doc>
</add>

Thanks,

Jae