From the documentation:
The SYS.XMLTYPE object was introduced in Oracle9 to encapsulate XML in the Oracle database. In Oracle9.2 this object type can be accessed from the Oracle Net 9.2 client. The TXMLType provides an easy interface to the SYS.XMLTYPE object type. The TXMLType object descends from TOracleObject, and can therefore be used anywhere that you can use a TOracleObject (for example, when assigning an object instance to a variable through SetComplexVariable).
The XML text of a TXMLType instance can be set during creation:
var
XML: TXMLType;
begin
XML := TXMLType.Create(MainSession, '<message>Hello World</message>');
try
XMLQuery.SetComplexVariable('xmlvar', XML);
XMLQuery.Execute;
finally
XML.Free;
end;
end;The XML text of a TXMLType instance can be retrieved through the XML read-only property.
The TOracleQuery.XMLField and TOracleObject.XMLAttr functions return a TXMLType instance for a field or attribute.
Note
The XMLType object can only be used with Oracle9.2.