Unique set values

Hi I have the following XML

<statResults>
 <statResult>
   <valSpecId>1</valSpecId>
   <methodology>parametric</methodology>
   <statName>ConditionalMean</statName>
   <parameter>0.05</parameter>
   <result>-0.951696710686655</result>
 </statResult>
 <statResult>
  <valSpecId>2</valSpecId>
  <methodology>parametric</methodology>
  <statName>ConditionalMean</statName>
  <parameter>0.05</parameter>
  <result>-219.796643247407</result>
  </statResult>
  <statResult>
  <valSpecId>1</valSpecId>
  <methodology>parametric</methodology>
  <statName>ConditionalMean</statName>
  <parameter>0.07</parameter>
  <result>-219.796643247407</result>
 </statResult>
 <statResult>
  <valSpecId>2</valSpecId>
  <methodology>parametric</methodology>
  <statName>ConditionalMean</statName>
  <parameter>0.07</parameter>
  <result>-219.787907827418</result>
 </statResult>
 <statResult>
  <valSpecId>2</valSpecId>
  <methodology>parametric</methodology>
  <statName>VaR</statName>
  <parameter>0.97</parameter>
  <result>3.26</result>
 </statResult>
  ...

I want to be able to return unique 3-tuple value consisting of methodology,
statName, and parameter. That is

 <statResult>
  <methodology>parametric</methodology>
  <statName>ConditionalMean</statName>
  <parameter>0.05</parameter>
 <statResult>
 <statResult>
  <methodology>parametric</methodology>
  <statName>ConditionalMean</statName>
  <parameter>0.07</parameter>
 <statResult>
 <statResult>
  <methodology>parametric</methodology>
  <statName>VaR</statName>
  <parameter>0.97</parameter>
 <statResult>

Thx,

Carlos Sanchez
The RiskMetrics Group


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