$ cat f.xml
<?xml version="1.0" encoding="utf-8"?>
<TheRoot>
 <Message>
  <MyNumber>001</MyNumber>
  <Registration>222</Registration>
  <GPS>
   <Year>2009</Year>
  </GPS>
  <LbtSession>
   <Year>2009</Year>
  </LbtSession>
 </Message>
 <Message>
  <MyNumber>887</MyNumber>
  <Registration>333</Registration>
  <Client>None</Client>
  <Type>Position</Type>
 </Message>
</TheRoot>
$ 
$ xml_split -vc Message f.xml
generating main file f-00.xml
generating f-01.xml
generating f-02.xml

$ cat f-00.xml
<?xml version="1.0" encoding="utf-8"?>
<TheRoot>
 <?merge  subdocs = 0 :f-01.xml?>
 <?merge  subdocs = 0 :f-02.xml?>
</TheRoot>
$ 
$ cat f-01.xml
<Message>
  <MyNumber>001</MyNumber>
  <Registration>222</Registration>
  <GPS>
   <Year>2009</Year>
  </GPS>
  <LbtSession>
   <Year>2009</Year>
  </LbtSession>
 </Message>
$ 
$ 
$ cat f-01.xml
<Message>
  <MyNumber>001</MyNumber>
  <Registration>222</Registration>
  <GPS>
   <Year>2009</Year>
  </GPS>
  <LbtSession>
   <Year>2009</Year>
  </LbtSession>
 </Message>
$