Editing Postcode Address File (section)

==Alias data==

The "alias file" is a supplementary file containing additional data which are not part of official postal addresses, including details that have changed over time, or have been amended by the public and then used. This file is used to identify these elements and [[cross-reference]] with the official postal address.

The alias file holds four types of record: locality, thoroughfare, delivery point alias, and county alias:

*The locality record – old short forms, local names, and 'postally-not-required' (PNR) details.
*The thoroughfare record – contains replacement street and road names for a given locality, thoroughfare or dependent thoroughfare combination.
*The delivery point alias record – holds additional information at given addresses, such as trading names and building names.
*The county record – holds [[Counties of the United Kingdom|traditional]], [[Administrative county|administrative]] and [[Postal counties of the United Kingdom|postal county]] information.

Royal Mail, in their guide to the data products<ref>[ftp://ftp.royalmail.com/Downloads/public/ctf/rm/PAF_Digest_Dec_03.pdf PAF Digest]{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}}, p12</ref> imply that the county alias information was provided when Royal Mail removed the former postal county from the main file.