Yes, there is the voluntary code. People who want to sell a product without GMOs have to comply with the voluntary code. People who want to sell a product that contains GMOs and indicate that fact on the product use the warning “contains GMOs“. They must comply with the voluntary code. As soon as you want to say “GMO“ on your product to indicate that it does, or does not, contain any, the voluntary code becomes mandatory.
Is that the question you were asking?