Using SYS_XMLGEN

[olmos]

I am using Oracle's SYS_XMLGEN in a query. According to Oracle, it is supposed to always return a well-formed XML document.

My Query
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SELECT SYS_XMLGEN(empno)
FROM emp WHERE ename LIKE 'SMITH%';

My Result is :
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SYS_XMLGEN(EMPNO)

<EMPNO>7369</EMPNO>


I thought it was supposed to have the xml version on the first line. like this-
<?xml version=''1.0''?>
<empno>7369</empno>

Is there some setting I must change, what am I doing wrong?
How do I make it create a well formed xml document?

Thanks,
olmos