The rule
Google's own product data page says to submit only valid GTINs, to provide one only if you are sure it is correct, and not to guess or make up a value. A product with an incorrect GTIN is disapproved. An empty field is safer than a wrong one.
What it means for a tool that fills or matches data
A tool that fills blanks must be allowed to say 'unknown'. A tool that matches old codes to new must never output an identifier that is not in your files. Both rules can be checked by a script.
- Every identifier in the output is in the source.
- Silence in a description gives 'unknown'.
- An unsure pair stays unsure.
Categories are a separate question
The same page marks the Google product category as optional and describes its category attributes as a way to override Google's own categorisation in specific cases. Check what each channel requires before paying for category work. Where a channel does require a taxonomy, supply it so a tool can be checked against it.
Which job fits
The attributes job fills size, colour, material and pack only where the description states them, with the quoted words. The old-to-new matching job maps changed codes with look-alikes on an unsure list. The category job assigns products only to categories in your tree or to review.
Sources and limits
- Google Merchant Center: product data specification Checked 2026-10-12.
- Submit only valid GTINs as defined in the official GS1 validation guide.
- Only provide a GTIN if you are sure it is correct; when in doubt, do not provide the attribute, for example do not guess or make up a value.
- If you submit a product with an incorrect GTIN value, the product will be disapproved.
- The google_product_category attribute is marked optional, and the product-category attributes are described as a way to override Google's automatic product categorisation in specific cases.