A group of data elements which together define an identifier for a comparison product in accordance with a specified scheme. At least one <ProductIdentifier> composite is mandatory within an occurrence of <ComparisonProductPrice>, to identify the product to which the comparison price applies. Repeatable with different identifiers for the same product.

It is strongly advised that the relationship between the comparison product and the product described in the <Product> record is defined in a <RelatedProduct> composite in P.23 – typically this might be <ProductRelationCode> 06 (related product is alternative format with same content as product) and may in many circumstances also be 13 (product is e-publication based on related product).