{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "type": "object",
    "patternProperties": {
        "^[A-Z0-9]{3}\\d{2}$": {
            "title": "Book code, follow the ID3xx pattern",
            "type": "object",
                "$ref": "bookdetails-schema.json#"
        }
    },
    "additionalProperties": false
}