grouping of query data in xml

[c k <shreeseva.learning@xxxxxxxxx>]

Hi friends,

I am working with some xml exporting functionality of our application. I am testing query_to_xml function supported in PostgreSQL 9.1. XML output should be 
 <accgroup>

  <accgroupid>1</accgroupid>
  <accgroupname>COMPANY ACCOUNT</accgroupname>

 <docs>

  <refaccdocid>638168</refaccdocid>
  <debit>10000.0000</debit>
  <credit>0.0000</credit>

 </docs>
 <docs>

 <refaccdocid>638168</refaccdocid>
  <debit>0.0000</debit>
  <credit>10000.0000</credit>

  </docs>

</accgroup>

but the output is as follows:
<row>
  <accgroup>acc group</accgroup>
  <accgroupid>1</accgroupid>
  <accgroupname>COMPANY ACCOUNT</accgroupname>
  <docs>docs</docs>
  <refaccdocid>638168</refaccdocid>
  <debit>10000.0000</debit>
  <credit>0.0000</credit>
</row>

<row>
  <accgroup>acc group</accgroup>
  <accgroupid>1</accgroupid>
  <accgroupname>COMPANY ACCOUNT</accgroupname>
  <docs>docs</docs>
  <refaccdocid>638168</refaccdocid>
  <debit>0.0000</debit>
  <credit>10000.0000</credit>
</row>

How can grouping on specific columns can be done in result xml through using query_to_xml?
I am expecting help from postgresql community as always.

Thanks

CPKulkarni