This new attribute was created for shops that offer custom goods without an identifier like GTIN or MPN. Custom goods are hand knitted sweaters or antique furniture or vintage items. The ‘Identifier Exists’ field can be used to indicate that an identifier does not exist for certain products: Identifier exists = false.
Everybody else, with ‘normal’ goods, will have to enter an identifier like GTIN or MPN. They do not have to add the “Identifier exists” field to their feed - when it is not provided, Google assumes that an identifier exists.
“Identifier exists” is not an easy way out for merchants that sell regular products but forgot to add an identifier to their feed. If an identifier for a given product does exist and ‘Identifier_exist’ field is set to ‘FALSE’ (so you are 'lying' to Google), that product can be banned.
Let’s say that you sell both ‘custom’ and ‘normal’ products.
For the custom goods without an identifier, you need to add ‘identifier exists = false” because there is nothing in the fields for UPC (=GTIN).
This means that ‘identifier exists = true” for your normal products:
Yes, for most products you need to have at least 2 out of these 3 fields: Brand, MPN and GTIN, as long as you don’t sell custom goods. In the words of Google:
That happens a lot. The best solution is to ask the manufacturers of your products for all MPNs or GTINs and add them to your shop. If that doesn't work, you’ll get away with mapping MPN from ID; then you’ll make the 2 out of 3, assuming that you do have brand. Read more about this in Brand, MPN and GTIN.
