How to generate a .ocs file manually

Hy !

If it is possible, How can I generate a .ocs file manually ? I see that .ocs file It is similar to a xml file. 

I try create one but not work !

Below is the xml I created manually:

<?xml version="1.0" encoding="UTF-8"?>

<REQUEST>

  <CONTENT>

    <HARDWARE>

      <DESCRIPTION>Server datacenter VM</DESCRIPTION>

      <LASTLOGGEDUSER>user</LASTLOGGEDUSER>

      <NAME>SERVER_HOST_NAME</NAME>

      <USERID>user</USERID>

      <VMSYSTEM>server</VMSYSTEM>

      <WORKGROUP>datacenter VM</WORKGROUP>

    </HARDWARE>

<USERS>

      <LOGIN>user</LOGIN>

    </USERS>

  </CONTENT>

  <DEVICEID>server</DEVICEID>

  <QUERY>INVENTORY</QUERY>

</REQUEST>

When I try inject to ocs server happens this error : 

ERROR: 400 Bad Request

OBS: When I use ocsinventory-agent to create .ocs and injet to server it works with success.