What is an OWPA?

OWPA – Objects without a postal address – are sourced from the OS MasterMap Topography Layer using relevant associated cartographic text. They are then given an Ordnance Survey generated geographic address.

How does it work?

OS MasterMap Address Layer 2 includes over one million OWPA, including features such as community halls, churches, public conveniences and utility works, all with straightforward and intuitively useful addresses.

Each OWPA contains up to four alternative unique classifications:

• Ordnance Survey’s field surveyors allocation – OS Base Function
• The Valuation Agency Offices’ SCAT code (Special Category) and PDesc (Primary Description)
• NLUD classification (National Land Use Database)

These classifications are all contained in a master look-up table.

So let’s take a look at how OS MasterMap Address Layer 2 creates an address.

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