let type_sql_of_xml = function
[ Xml.Element("ti",_,[Xml.PCData t]);
Xml.Element("ti",_,[s1]);
Xml.Element("ti",_,[s2]);
] ->
(unescape t,
opt_of_xml string_of_xml s1,
opt_of_xml string_of_xml s2)
| e -> fail (Xml.Element ("list",[],e)) "type_sql_of_xml"