{
  "@context": {
    "ex": "http://example.org/ns/",
    "prop": {
      "@id": "ex:prop",
      "@container": "@index",
      "@index": "ex:name"
    }
  },
  "prop": {
    "foo": { "@id": "ex:foo"},
    "bar": { "@id": "ex:bar"}
  }
}