what is a unique reference number
A NLPG Unique Property Reference Number (UPRN) is an attribute of a Basic Land and Property Unit (BLPU).It is a unique reference number that links together information and is used to cross-reference associated data to.PRNs are integers (numbers) that can be up to 12 digits in length; they can therefore be less than 12 digits long and do not require leading zeros. However some gazetteer database applications will pad UPRNs that are less than 12 digits with zeros.