{
  "composedtype": {
    "uri": "tag:www.example.com:rx/person",
    "schema": {
      "type": "//rec",
      "required": { "firstname": "//str",
                    "lastname": "//str" },
      "optional": { "middlename": "//str" }
    }
  },

  "schema": {
    "type"   : "tag:www.example.com:rx/person",
    "unknown": "this will cause an explosion"
   },

  "invalid": true
}