DOP on canned tomatoes means and stands for Denominazione d'Origine Protetta.
DOP or Denominazione d'Origine Protetta is Italian for Protected Designation of Origin.
The designation is essentially a geographical indication that guarantees that the tomatoes are grown and also processed in a specific region of Italy "the Agro Sarnese Nocerino area.
For San Marzano tomatoes, the DOP certification ensures that the tomatoes are grown in the designated region, using specific seeds and farming practices, and are processed according to established guidelines.
DOP is a European Union certification that ensures a product's quality and characteristics are tied to a specific geographic area and traditional production methods.
The DOP label on canned tomatoes is a guarantee of authenticity and helps consumers distinguish genuine San Marzano tomatoes from those that may be labeled as such but are not actually from the designated area or produced using traditional methods.
Authentic DOP San Marzano tomatoes will typically be whole peeled or halved and canned, not diced or pureed.
When your see the DOP on canned tomatoes it means that the tomatoes have been officially recognized for it's unique qualities and connection to a specific Italian region and it's traditional farming practices.