Generate Valid XML from pl/sql

Question

Hi,
A new-bee here. I want to know how to generate a valid xml document. I have a schema which by the way includes two other schemas. This is the code I am using but I don't know how to make sure that I insert the child nodes in the right sequence. Any sample code that you guys can provide would be greatly appreciated.
FUNCTION GenerateOrderXML(
          o_ErrorCode     OUT     NUMBER,
          o_ErrorText     OUT     VARCHAR2,
          i_AccountID     IN     document.documentid%TYPE,
          i_OrderName IN VARCHAR2) RETURN XMLType
IS
     v_Doc     XMLDOM.DOMDocument;
     v_MainNode     XMLDOM.DOMNode;
     v_RootElmt     XMLDOM.DOMElement;
     v_RootNode     XMLDOM.DOMNode;
     v_TmpCLOB     CLOB := ' ';
CURSOR CURSOR_SERVOBJ
          IS
          SELECT XMLTAG, XMLVALUE FROM SERVICEOBJECT
               WHERE SERVICEOBJECT.ID < 500
               ORDER BY SEQUENCE;
-- Create xml root element
     v_Doc := XMLDOM.newDOMDocument;
     v_MainNode := XMLDOM.makeNode(v_Doc);
     v_RootElmt := XMLDOM.createElement(v_Doc, 'OrderRequest');
     v_RootNode := XMLDOM.appendChild(v_MainNode, XMLDOM.makeNode(v_RootElmt));
     -- Add OrderName, OrderType
     AddChild(v_Doc, v_RootNode, 'orderName', i_OrderName);
     AddChild(v_Doc, v_RootNode, 'orderType', 'NA');
     -- Add all attributes
     FOR v_NameValue IN CURSOR_SERVOBJ
     LOOP
          AddChild(v_Doc, v_RootNode, v_NameValue.XMLTAG, v_NameValue.XMLVALUE);
     END LOOP;
     --     XMLDOM.writeToBuffer(v_Doc, v_Buffer);
     XMLDOM.writeToClob(v_Doc, v_TmpCLOB);
     o_ErrorCode := 0;
     RETURN XMLType.createXML(v_TmpClob);
END;

Answer 1

The r was a typo. The messge is correct.
Here is another problem I am having. I can't import a schema that includes another schema. When I try to register the third schema I get the following error. The first two register without any errors and when I run this
select schema_url from user_xml_schemas;
I see
http://www.bbc.com/XMLSchema/sfi.xsd
http://www.bbc.com/XMLSchema/ProductModel.xsd
So why is my third schema not importing? Can you point me to any good documentation/tutorials on XML DB.
Note: Thank you for your help so far.
ERROR at line 1:
ORA-31000: Resource 'ProductModel.xsd' is not an XDB schema document
ORA-06512: at "XDB.DBMS_XMLSCHEMA_INT", line 0
ORA-06512: at "XDB.DBMS_XMLSCHEMA", line 26
ORA-06512: at "XDB.DBMS_XMLSCHEMA", line 131
ORA-06512: at line 6
1st Schema Heading
<xsd:schema xmlns="http://www.bbc.com/XMLSchema/bfi.xsd" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.bbc.com/XMLSchema/bfi.xsd" elementFormDefault="qualified">
2nd Schema Heading
<xsd:schema xmlns="http://www.bbc.com/XMLSchema/ProductModel.xsd" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.bbc.com/XMLSchema/ProductModel.xsd" elementFormDefault="qualified">
3rd Schema Heading
<xsd:schema xmlns="http://www.bbc.com/XMLSchema/ResourceOrder.xsd" xmlns:qb="http://www.bbc.com/XMLSchema/ProductModel.xsd" xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.bbc.com/XMLSchema/ResourceOrder.xsd" elementFormDefault="qualified">
<xsd:import namespace="http://www.bbc.com/XMLSchema/ProductModel.xsd" schemaLocation="ProductModel.xsd"/>