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OS MasterMap Address Layer 2 frequently asked questions

What are the benefits of Address Layer 2 over Address Layer?

OS MasterMap® Address Layer 2 builds on the success of Ordnance Survey's current addressing products by offering significant enhancements such as geographic alternatives, building names aliases, Welsh alternatives and two new datasets – Objects without postal addresses (OWPAs) and Multi-occupation without postal addresses (MOWPAs). All addresses contain up to four classifications, together with Ordnance Survey’s unique identifier – the TOID.

Address Layer 2 contains a range of new data, such as:

- Alternative geographic addresses: for example, 12 Old Town, London, SW4 0JY is also available as 12 Old Town, Clapham, London, SW4 0JY. This is provided in BS7666 part 3 format.

- Building name aliases: buildings that may be known by a name as well as a house number. For example, Railway Cottage may also be known as 61 Station Road.
Welsh alternatives – for example, 13 Mill Street, Aberystwyth, SY23 1HZ could also be 13 Dan Dre, Aberystwyth, SY23 1HZ.

- Classifications: each address is classified as either residential or commercial. These are then further analysed where the trading name provides further details, for example, Barclays Bank – bank, and W H Smith – retail.  The detailed classifications are sourced from Ordnance Survey, Valuation Office Agency and the National Land Use Database descriptions.

- Objects without postal addresses (OWPAs): over 1 million buildings and other features that do not have a postal address, such as churches, community centres, depots, masts and so on. These have all been classified as covered above, and given a geographic address; for example, Community Hall, Hulse Road, Southampton, SO15 2JW.

- Multi-occupation without postal addresses (MOWPAs): details of individual households that currently do not have mail delivered to their own letter box, such as flats; for example, 'Flat A, Flat B' at 1 London Road, Maidstone, Kent, ME16 8QL. These are all supplied complete with the parent delivery address. The first release will contain 150 000 structured addresses, and this will grow during subsequent data updates. These are supplemented by a total of over 400 000  'multi-occupation' counts, which are included within the address theme. These cover buildings where multi-occupation occurs, such as halls of residence, old peoples' home, but the internal details are not known such as flats.

- Integration with other OS MasterMap layers: the address TOID is linked to the Topographic and Integrated Transport NetworkTM (ITN) TOIDs.

- Cross reference to external datasets: this currently includes Royal Mail’s Unique Delivery Point Reference Number (UDPRN) and Unique Multi-Residence Reference Number (UMRRN) and the Valuation Office Agency’s Unique Address Reference Number (UARN).

PAF and Royal Mail are registered trademarks of Royal Mail Group plc.


Where does the OS MasterMap Address Layer 2 data come from?

Similarly to OS MasterMap Address Layer data, Address Layer 2 data is based upon matching the Royal Mail Postcode Address File (PAF) to the buildings in the Topography Layer. The link between the Address and the Topography Layer building is twofold: firstly, implicitly based upon spatial intersection of the matched address feature coordinate position and the topographic area building feature it relates to; and secondly, explicitly since the Address Layer 2 attributes include the TOID of that related building feature. New or changed addresses are notified to Ordnance Survey via a monthly update to PAF and are matched to the Topography Layer, either by field visits or by relating to information already captured.

OS MasterMap Address Layer 2 also offers significant enhancements to Address Layer, such as geographic alternatives, building name aliases, Welsh alternatives and two new datasets – Objects without postal addresses (OWPAs) and Multi-occupancy without postal addresses (MOWPAs). This data is sourced from Royal Mail and Ordnance Survey.


Are all addresses in OS MasterMap Address Layer 2?

OS MasterMap Address Layer 2 contains addresses supplied to Ordnance Survey in the Royal Mail’s PAF and Multi-Residence File (Multi-occupancy without postal addresses or MOWPAs), together with addresses for the Objects without postal addresses (OWPAs) that have been derived from a number of different Ordnance Survey datasets.


How do I migrate from ADDRESS-POINT to Address Layer 2?

Both products are available in CSV, so format should not be an issue, although there is significanltly more data in OS MasterMap® Address Layer 2. Organisations will need to sign the applicable Address Layer 2 product schedules that accompany the Framework Direct Licence.

For further details, please contact your account manager or Ordnance Survey at DigitalSalesEnquiries@ordnancesurvey.co.uk.


Are the OS MasterMap Address Layer 2 addresses in the right place?

Each address is coordinated on the National Grid, with eastings and northings normally quoted to a resolution of 0.1 metre. The coordinate is positioned within the building the address applies to (if applicable) and the TOID of that building is provided; the coordinate does not reflect the precise location of the delivery point to the building. The positional quality of the coordinate is specified by the positionalQuality component of the addressStatus attribute of the address feature as follows:

Final – Surveyed: addresses that are matched to a final position.
Provisional – Approximate: addresses matched to an approximate position (usually within 50 m); for example, a temporary building such as a site office.
Provisional – Estimate: addresses matched to the centre of a postcode unit (for example, SO40 8EY).
Provisional – Postcode Sector Mean: addresses matched to the centre of a postcode sector (for example, SO40 8).
Provisional – Postcode Unit Mean: addresses that have only estimated positions, usually because they have a new postcode that does not correlate with any existing postcode.

Some addresses are non-geographic, such as Post Office boxes, which are usually matched to the relevant Royal Mail sorting office; this will not be the point where the mail is actually delivered.

While addresses and buildings are maintained simultaneously (both in capture of real-world change and in positional accuracy improvement processes), it is not yet possible to generate the OS MasterMap Address Layer 2 and Topography Layer products from the maintained database simultaneously. This may mean that, very occasionally, a user may find an address coordinate outside a topographic building, even though they downloaded both layers on the same day.

Post Office is a registered trademark of Royal Mail Group plc.

Are there any plans to withdraw ADDRESS-POINT or Address Layer?

There are no plans to withdraw ADDRESS-POINT or OS MasterMap Address Layer at this stage.


Will dual running of Address Layer 2 and ADDRESS-POINT be available?

Yes: you may migrate from ADDRESS-POINT to the Address Layer within the constraints of your existing contract. Ordnance Survey is aware of this issue and will help you with contractual requirements to assist your migration. Please contact your account manager or Ordnance Survey on DigitalSalesEnquiries@ordnancesurvey.co.uk for details.Why are some Valuation Office Agency (VOA) unique identifiers (UARNs) missing?

In OS MasterMap Address Layer 2 there are a number of Royal Mail and Ordnance Survey unique identifiers that do not have a corresponding unique identifier from the VOA; that is, there's no Unique Address Reference Number (UARN).

Matching of the VOA's Council Tax and Non Domestic Rates data is done in three stages: automated processing using software, manual review of any discrepancies and, finally, field review for any remaining items. To date, the first stage has been completed, and manual review and field work has now started. As this work progresses, additional matches will be determined and the number of UARNs will increase. In addition, it should be noted that since the VOA only covers England and Wales, UARNs for Scotland will not be available.

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For general enquiries, complaints, feedback or suggestions, email: customerservices@ordnancesurvey.co.uk or call us on 08456 05 05 05