+-- | A further refinement of 'FromXmlFk'. These types need not only a
+-- foreign key to a parent in order to make the XML -> DB
+-- conversion, but also two foreign keys to away/home teams (as
+-- represented in "TSN.Team").
+--
+class (Child a, ToDb a) => FromXmlFkTeams a where
+ -- | The function that produces a @Db a@ out of a parent foreign
+ -- key, two team foreign keys, and an @a@. The parameter order makes
+ -- it easier to map this function over a bunch of things.
+ from_xml_fk_teams :: DefaultKey (Parent a)
+ -> DefaultKey Team -- ^ The away team FK
+ -> DefaultKey Team -- ^ The home team FK
+ -> a
+ -> Db a
+
+