id - Unique ID of product. This field must be constant in your feed.affiliate link – Link to product with your affiliate parameter.is in stock – Supported values: "1", "true", "on" and "yes", "0", "false", "off", "no".availability - Supported values: "in stock", "out of stock".direct link – Direct URL on original product page without redirects and affiliate parameters.gtin - EAN 13-digit number like 3001234567892.