{
    "title": "Schema for RESTful Open Annotation in JSON-LD",
    "$schema": "http://json-schema.org/draft-04/schema#",

    "definitions": {
	"listOfUri": {
	    "oneOf": [
		{
		    "type": "string",
		    "format": "uri"
		},
		{
		    "type": "array",
		    "items":{
			"type":"string",
			"format": "uri"
		    }
		}
	    ]
	},
	"xsd:dateTime": {
	    "type": "string",
	    "pattern": "^[1-9][0-9]{3}-[0-1][0-9]-[0-3][0-9]T[0-9]{2}:[0-9]{2}:[0-9]{2}(Z?|[+-].+)$"
	}
    },

    "type": "object",
    "properties": {
        "@context": {
            "description": "Used to define the short-hand names that are used throughout a JSON-LD document.",
            "type": ["object", "string", "array", "null"]
        },
	"@graph": {
	    "type": ["array"],
	    "items": {
		"type": ["object"],
		"properties": {
		    "body": {
			"description": "the comment or other descriptive resource",
			"oneOf": [
			    {"$ref": "#/definitions/listOfUri"},
			    {
				"type": "object",
				"properties": {
				    "@id": {"type": "string", "format": "uri"}
				},
				"additionalProperties": true
			    }
			]
		    },
		    "target": {
			"description": "the body is somehow about",
			"$ref": "#/definitions/listOfUri"
		    },
		    "annotatedBy":  {
			"description": "the agent creating the annotation",
			"$ref": "#/definitions/listOfUri"
		    },
		    "serializedBy": {
			"description": "the agent serialzing the annotation",
			"$ref": "#/definitions/listOfUri"
		    },
		    "serializedAt": {
			"description": "the time when the annotation is serialized",
			"$ref": "#/definitions/xsd:dateTime"
		    },
		    "annotatedAt": {
			"description": "the time when the annotation is created",
			"type": "string",
			"$ref": "#/definitions/xsd:dateTime"
		    },
		    "@id": {
			"type": "string",
			"format": "uri"
		    }
		},
		"required": ["target", "@id"]
	    }
	}
    }
}