{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Check @context value",
  "description": "'http://www.w3.org/ns/anno.jsonld must be' an @context value (Section 3.1)",
  "assertionType": "must",
  "expectedResult": "valid",
  "errorMessage": "Error: 'http://www.w3.org/ns/anno.jsonld' is not an @context value.",
  "type": "object",
  "properties": {
    "@context": {
      "oneOf": [
        { "type": "string",
          "$ref": "#/definitions/contextValue" },
        { "type": "array",
          "$ref": "#/definitions/contextArray" }
      ]
    }
  },
  "definitions": {
    "contextValue":
       { "enum": [ "http://www.w3.org/ns/anno.jsonld" ] },
    "contextArray":
       { "not":
          { "items":
             { "not":
                { "type": "string",
                  "$ref": "#/definitions/contextValue" } }
           }
     }
  }
}