{
    "$schema": "http://json-schema.org/draft-03/schema",
    "additionalProperties": false,
    "properties": {
        "previewable": {
            "required": false,
            "type": ["string", "null"],
            "description": "Whether or not the product is previewable."
        },
        "preorder_date": {
            "required": false,
            "type": ["string", "null"],
            "pattern": "^[0-9]{4}-[0-9]{2}-[0-9]{2}$",
            "description": "The date when preorders of the product begin (or began)."
        },
        "release_date": {
            "required": false,
            "type": ["string", "null"],
            "pattern": "^$|^[0-9]{4}-[0-9]{2}-[0-9]{2}$",
            "description": "The date when the product will be (or was) released."
        },
        "sale_start_date": {
            "required": false,
            "type": ["string", "null"],
            "pattern": "^$|^[0-9]{4}-[0-9]{2}-[0-9]{2}$",
            "description": "The date when sales of the product begin (or began)."
        }
    },
    "required": true,
    "type": "object"
}