[
    {
        "type": "text",
        "name": "isbn",
        "label": "ISBN",
        "required": true,
        "editable": true,
        "hidden": false
    },
    {
        "type": "number",
        "name": "retail_price",
        "label": "Maximum Retail Price",
        "required": true,
        "editable": true,
        "hidden": false
    },
    {
        "type": "number",
        "name": "quantity",
        "label": "Number of Items",
        "required": true,
        "editable": true,
        "hidden": false
    },
    {
        "type": "calculated",
        "name": "total_amount",
        "label": "Total Amount",
        "required": false,
        "editable": true,
        "hidden": false,
        "fields": ["quantity", "retail_price"],
        "expression": "quantity * retail_price"
    }
]