
SCHEMA new_schema;

ENTITY Person
   ABSTRACT SUPERTYPE OF (ONEOF (Male, Female));
     name: STRING;
     mother: OPTIONAL Female;
     father: OPTIONAL Male;
END_ENTITY;

ENTITY Female
   SUBTYPE OF (Person);
END_ENTITY;

ENTITY Male
   SUBTYPE of (Person);
END_ENTITY;


END_SCHEMA;

