AddressBase Specification FAQs

This page is designed to help you with common queries which might arise as part of changing to the new specification for AddressBase and AddressBase Plus.

Changes to AddressBase and AddressBase Plus

I have not loaded Epoch data from before Epoch 35, what should I do?

As Epoch 35 is a Full Supply you do not necessarily have to load previous epochs. If you simply load Epoch 35 your data holdings will be complete.

But if your business has a requirement for archiving and knowing change history, you may still wish to load all of your previous supplies before Epoch 35.

Have the GML Schema files changed?

Yes, as part of the specification change the GML schema files have also been updated.

AddressBase -

AddressBase Plus -

Please note: The original schema files are still avaliable, but for Epoch 35 onwards you need to use the new schema files.

Where can I find the new Technical Specification documents?

The new Technical Specification documents can be found on the support pages of the appropriate products -

AddressBase Support Page

AddressBase Plus Support Page

What coordinate system and SRID are the Latitude and Longitude Columns?

The Latitiude and Longitude columns are published in ETRS89. The correct SRID for this is EPSG:4258.

How is the new Country Code created?

The Country Code is created by comparing the address location with the OS Boundary Line product. 

Any records with a 'J' code (Unassigned) currently fall outside the definition of England, Wales or Scotland. These will most likely be offshore windfarms.

I have only got two values in the Last Update Field, is this correct?


As part of the specification change, all date columns within the product have been improved. In order to make this improvement it has been required to re-baseline the last update field.

This means you should have two dates - 22/08/2015 and 23/08/2015

If the record has the date 22/08/2015 this means no change has been made to this record between Epoch 34 and Epoch 35, other than the columns being affected by the specification change. If the date is 23/08/2015 the record has an attribute which existed in Epoch 34 and has changed in Epoch 35 independent of the specification changes.

AddressBase Plus Changes

Why do I now have more TOID cross references?

As part of the specification change, work has also been undertaken to improve key elements of the product.

OS Mastermap Topography Layer TOIDs are now populated for all records which fall within the capture area of OS Mastermap Topography Layer.

OS Mastermap Integrated Networks Layer TOIDs are now populated for all records; this is created by performing a 'find my nearest' search.

How have the Ward and Parish codes been populated?

As a further enhancement in Epoch 35 the completeness of the Ward and Parish code informaiton has been improved.

To create a Ward and / or Parish code the OS Boundary Line product is used. If an address record falls within a Ward or Parish, the Office for National Statistics Code is allocated to the UPRN and is present in the AddressBase Plus product.

Please note not all records will have a Parish code as not all addresses are within a Parish.

Many Scottish textual fields seem to have changed their case, why is this?

Epoch 35 has also included an enhancement to bring consistency to the text fields. To this end, all textual fields will now be delievered in UPPER CASE independent of their submitting authority.

Why have I got more records in my supply?

The background logic for AddressBase Plus was changed as part of the specification change. This means that all data sources; Local Authorities, Royal Mail and Valuation Office Agency, are now used to determine if an address record is live, and therefore should be part of the AddressBase Plus product.