| `Remark -> Xml.xml_empty "flavour" [None, "value", "remark"]
| `Theorem -> Xml.xml_empty "flavour" [None, "value", "theorem"]
| `Variant -> Xml.xml_empty "flavour" [None, "value", "variant"]
+ | `Axiom -> Xml.xml_empty "flavour" [None, "value", "axiom"]
in
let xml_attr_of = function
| `Generated -> Xml.xml_empty "generated" []