用xslt将xml中的多个属性分组

I have the following xml

我有以下xml。

<smses>
  <sms address="87654321" type="1" body="Some text" readable_date="3/09/2011 2:16:52 PM" contact_name="Person1" />
  <sms address="87654321" type="2" body="Some text" readable_date="3/09/2011 2:36:41 PM" contact_name="Person1" />
  <sms address="87654321" type="1" body="Some text" readable_date="3/09/2011 2:16:52 PM" contact_name="Person1" />
  <sms address="123" type="2" body="Some text" readable_date="3/09/2011 10:56:24 AM" contact_name="Person2" />
  <sms address="123" type="1" body="Some text" readable_date="3/09/2011 10:57:52 AM" contact_name="Person2" />
  <sms address="123" type="2" body="Some text" readable_date="3/09/2011 10:56:24 AM" contact_name="Person2" />
  <sms address="12345678" type="1" body="Some text" readable_date="3/09/2011 11:21:16 AM" contact_name="Person3" />
  <sms address="12345678" type="2" body="Some text" readable_date="3/09/2011 11:37:21 AM" contact_name="Person3" />

  <sms address="12345" type="2" body="Some text" readable_date="28/01/2011 7:24:50 PM" contact_name="(Unknown)" />
  <sms address="233" type="1" body="Some text" readable_date="30/12/2010 1:13:41 PM" contact_name="(Unknown)" />
</smses>
<smses>