{
    "additionalProperties": false,
    "description": "common json schema for time-based event aggregation records (datum)",
    "properties": {
        "_id": {
            "description": "unique url-friendly base64 encoded, utf8 endoded concatenation identifier",
            "type": "string"
        },
        "_timestamp": {
            "_format": "date-time",
            "description": "ISO8601 combined date and time in UTC e.g. '2014-12-01T00:00:00+00:00'",
            "type": "string"
        },
        "period": {
            "description": "The period covered by each data point from the _timestamp",
            "enum": [
                "hour",
                "day",
                "week",
                "month",
                "quarter"
            ]
        }
    },
    "required": [
        "_id",
        "_timestamp",
        "period"
    ],
    "title": "aggregate-base",
    "type": "object"
}