JSON format of Google Product Data Specification, as seen here - https://support.google.com/merchants/answer/7052112?hl=en

google_product_data_specifications.json

[
    {
        "slug": "id",
        "description": "Your product’s unique identifier",
        "schema": "Product.sku",
        "group": "basic"
    },
    {
        "slug": "title",
        "description": "Your product’s name",
        "schema": "Product.name",
        "group": "basic"
    },
    {
        "slug": "description",
        "description": "Your product’s description",
        "schema": "Product.description",
        "group": "basic"
    },
    {
        "slug": "link",
        "description": "Your product’s landing page",
        "schema": "Offer.url",
        "group": "basic"
    },
    {
        "slug": "image_link",
        "description": "The URL of your product’s main image",
        "schema": "Product.image",
        "group": "basic"
    },
    {
        "slug": "additional_image_link",
        "description": "The URL of an additional image for your product",
        "schema": "",
        "group": "basic"
    },
    {
        "slug": "mobile_link",
        "description": "Your product’s mobile-optimized landing page when you have a different URL for mobile and desktop traffic",
        "schema": "",
        "group": "basic"
    },
    {
        "slug": "availability",
        "description": "Your product's availability",
        "schema": "Offer.availability",
        "group": "price"
    },
    {
        "slug": "availability_date",
        "description": "The date a pre-ordered product becomes available for delivery",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "cost_of_goods_sold",
        "description": "The costs associated with the sale of a particular product as defined by the accounting convention you set up. These costs may include material, labor, freight, or other overhead expenses. By submitting the COGS for your products, you gain insights about other metrics, such as your gross margin and the amount of revenue generated by your ads and free listings.",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "expiration_date",
        "description": "The date that your product should stop showing",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "price",
        "description": "Your product’s price",
        "schema": "Offer.priceSpecification",
        "group": "price"
    },
    {
        "slug": "sale_price",
        "description": "Your product's sale price",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "sale_price_effective_date",
        "description": "The date range during which the product’s sale_price applies",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "unit_pricing_measure",
        "description": "The measure and dimension of your product as it is sold",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "unit_pricing_base_measure",
        "description": "The product’s base measure for pricing (e.g. 100ml means the price is calculated based on a 100ml units)",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "installment",
        "description": "Details of an installment payment plan",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "subscription_cost",
        "description": "Details a monthly or annual payment plan that bundles a communications service contract with a wireless product",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "loyalty_points",
        "description": "The number and type of loyalty points a customer receives when buying a product",
        "schema": "",
        "group": "price"
    },
    {
        "slug": "google_product_category",
        "description": "Google-defined product category for your product",
        "schema": "",
        "group": "category"
    },
    {
        "slug": "product_type",
        "description": "Product category that you define for your product",
        "schema": "",
        "group": "category"
    },
    {
        "slug": "brand",
        "description": "Your product’s brand name",
        "schema": "Product.brand",
        "group": "identifiers"
    },
    {
        "slug": "gtin",
        "description": "Your product’s Global Trade Item Number (GTIN)",
        "schema": "Product.isbn,Product.gtin8,Product.gtin12,Product.gtin13,Product.gtin14",
        "group": "identifiers"
    },
    {
        "slug": "MPN",
        "description": "Your product’s Manufacturer Part Number (mpn)",
        "schema": "Product.mpn",
        "group": "identifiers"
    },
    {
        "slug": "identifier_exists",
        "description": "Use to indicate whether or not the unique product identifiers (UPIs) GTIN, MPN, and brand are available for your product.",
        "schema": "",
        "group": "identifiers"
    },
    {
        "slug": "condition",
        "description": "The condition of your product at time of sale",
        "schema": "Offer.itemCondition",
        "group": "product_description"
    },
    {
        "slug": "adult",
        "description": "Indicate a product includes sexually suggestive content",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "multipack",
        "description": "The number of identical products sold within a merchant-defined multipack",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "is_bundle",
        "description": "Indicates a product is a merchant-defined custom group of different products featuring one main product",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "energy_efficiency_class",
        "description": "Your product’s energy label",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "min_energy_efficiency_class",
        "description": "Your product’s energy label",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "max_energy_efficiency_class",
        "description": "Your product’s energy label",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "age_group",
        "description": "The demographic for which your product is intended",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "color",
        "description": "Your product’s color(s)",
        "schema": "Product.color",
        "group": "product_description"
    },
    {
        "slug": "gender",
        "description": "The gender for which your product is intended",
        "schema": "Product.audience.suggestedGender",
        "group": "product_description"
    },
    {
        "slug": "material",
        "description": "Your product’s fabric or material",
        "schema": "Product.material",
        "group": "product_description"
    },
    {
        "slug": "pattern",
        "description": "Your product’s pattern or graphic print",
        "schema": "Product.pattern",
        "group": "product_description"
    },
    {
        "slug": "size",
        "description": "Your product’s size",
        "schema": "Product.size",
        "group": "product_description"
    },
    {
        "slug": "size_type",
        "description": "Your apparel product’s cut",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "size_system",
        "description": "The country of the size system used by your product",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "item_group_id",
        "description": "ID for a group of products that come in different versions (variants)",
        "schema": "Product.inProductGroupWithID",
        "group": "product_description"
    },
    {
        "slug": "product_detail",
        "description": "Technical specifications or additional details of your product",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "product_highlight",
        "description": "The most relevant highlights of your products",
        "schema": "",
        "group": "product_description"
    },
    {
        "slug": "ads_redirect",
        "description": "A URL used to specify additional parameters for your product page. Users will be sent to this URL rather than the value that you submit for link or mobile_link",
        "schema": "",
        "group": "shopping_campaigns"
    },
    {
        "slug": "promotion_id",
        "description": "An identifier that allows you to match products to Merchant promotions",
        "schema": "",
        "group": "shopping_campaigns"
    },
    {
        "slug": "excluded_destination",
        "description": "A setting that you can use to exclude a product from participating in a specific type of advertising campaign",
        "schema": "",
        "group": "destinations"
    },
    {
        "slug": "included_destination",
        "description": "A setting that you can use to include a product in a specific type of advertising campaign",
        "schema": "",
        "group": "destinations"
    },
    {
        "slug": "shopping_ads_excluded_country",
        "description": "A setting that allows you to exclude countries where your products are advertised on Shopping ads.",
        "schema": "",
        "group": "destinations"
    },
    {
        "slug": "shipping",
        "description": "Shipping costs are required for Shopping ads for items with the following countries of sale: Australia, Austria, Belgium, Canada, Czechia, France, Germany, Ireland, Israel, Italy, the Netherlands, Poland, South Korea, Spain, Switzerland, the UK, and the US",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "shipping_label",
        "description": "Label that you assign to a product to help assign correct shipping costs in Merchant Center account settings",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "shipping_weight",
        "description": "The weight of the product used to calculate the shipping cost",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "shipping_length",
        "description": "The length of the product used to calculate the shipping cost by dimensional weight",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "shipping_width",
        "description": "The width of the product used to calculate the shipping cost by dimensional weight",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "shipping_height",
        "description": "The height of the product used to calculate the shipping cost by dimensional weight",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "ships_from_country",
        "description": "A setting that allows you to provide the country from which your product will typically ship.",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "transit_time_label",
        "description": "Label that you assign to a product to help assign different transit times in Merchant Center account settings.",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "max_handling_time",
        "description": "The longest amount of time between when an order is placed for a product and when the product ships.",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug": "min_handling_time",
        "description": "The shortest amount of time between when an order is placed for a product and when the product ships.",
        "schema": "",
        "group": "shipping"
    },
    {
        "slug" : "tax",
        "description": "Your product’s sales tax rate in percent",
        "schema" : "",
        "group": "tax"
    },
    {
        "slug": "tax_category",
        "description": "A category that classifies your product by specific tax rules",
        "group": "tax",
        "schema": ""
    }
]