This technical specification provides detailed technical information about Code-Point Open. It is targeted at technical users and software developers.
Code-Point Open is a dataset that contains postcode units for Great Britain, each having a notional geographical location. Postcodes are an alphanumeric abbreviated form of an address. Postcode units are unique references and identify an average of 15 addresses. In some cases, where an address receives a substantial amount of mail, a postcode will apply to only one address and is defined as a large-user postcode. The maximum number of addresses in a postcode is 100.
| Glossary Term | Definition |
|---|---|
| Attribute | Description |
|---|---|
An asterisk (*) indicates that the attribute is blank when the entity does not have a code. The Welsh Local Health Boards are included in Code-Point Open.
Each postcode unit location – also known as CPLC (Code-Point Location Coordinate) – is coordinated on the respective National Grid, with Eastings and Northings quoted to a resolution of 1m. The accuracy of each postcode unit coordinate pair is defined by the positional quality indicator (PQI), which provides a quality statement of that Code-Point Open record. There are seven PQI values for the positional quality:
| PQI | Description |
|---|---|
addressed premise
A permanent or non-permanent building structure with an address being a potential delivery point for Royal Mail. Examples include a house, a flat within a block of flats, a caravan site, or an organisation.
building
A physical, walled structure connected to foundations that has, or will have, a roof. This includes buildings surveyed at foundation stage.
CPLC (Code-Point location coordinate)
A National Grid reference for each postcode unit. It is a two-dimensional coordinate point to a resolution of 1 metre. Coordinates are attributed from GridLink using an accuracy hierarchy.
Country code
The code used by the Office of National Statistics to indicate the country in which the Code-Point georeference lies. This has replaced the PAF update date field.
Country Code
England: E92000001 Scotland: S92000003 Wales: W92000004 N Ireland: N92000002
Comma-separated values (CSV)
The CSV file format is commonly used to exchange data between different applications, for example, Microsoft Excel and Access. Being text files, CSV files can also be viewed in Notepad.
delivery point
A Royal Mail-defined point to which mail is delivered. This may be a property (private address), organisation, mailbox, or even, very rarely, the name of an individual.
GridLink
A joined-up Government initiative involving Royal Mail, the Office for National Statistics (ONS), National Records of Scotland (NRS), Land & Property Services, and Ordnance Survey.
inward code or incode
See postcode.
matched address
An address resulting from a match between the OS MasterMap Topography Layer data and PAF, which has been allocated a coordinate position.
National Grid
A unique referencing system that can be applied to all Ordnance Survey maps of Great Britain (GB) at all scales.
National Grid reference (NGref)
The National Grid provides a unique reference system that can be applied to all Ordnance Survey maps of Great Britain. The map of Great Britain is covered by 100 km by 100 km grid squares.
non-geographic postcodes
Special non-geographic postcodes are allocated to single organisations who receive an exceptionally large amount of mail. These are included in Code-Point Open.
outward code or outcode
See postcode.
Postcode Address File (PAF)
PAF now contains the postal addresses and postcodes of approximately 28 million delivery points in Great Britain.
Postal Address Location Feed (PALF)
The PAL Feed is provided to Ordnance Survey from GeoPlace, who have geocoded the PAF feed from Royal Mail, using source coordinates from Local Authorities in England, Wales, and Scotland.
positional quality indicator (PQI)
The positional quality indicator is a flag used to indicate the positional accuracy of the coordinates allocated to each postcode record. There are seven PQI values for the positional quality of CPLCs.
postal address
A postal address is a delivery point that is currently receiving mail. There may be many delivery points within an individual building structure as shown in OS MasterMap Topography Layer data.
postcode
An abbreviated form of address made up of combinations of between six and eight alphanumeric characters. A postcode may cover between 1 and 100 addresses. The average number of addresses per postcode is 15.
postcode area
An area given a unique alphabetic coding by Royal Mail to facilitate the delivering of mail. The area is identified by one or two alpha characters at the start of the full postcode.
postcode district
A sub-area of the postcode area, specified by the character sub-string within the first half of a full postcode, which may be numeric, alphabetic, or alphanumeric.
postcode sector
A sub-area of a postcode district, whose area is identified by the number third from the end of a full postcode.
postcode unit
A sub-area of a postcode sector, indicated by the two letters of the inward postcode, which identifies one or more small-user postcode delivery points or an individual large-user postcode.
Postcode
Contains elements for postal area, district, sector, and unit.
Positional quality indicator (PQI)
A flag used to indicate the positional accuracy of the coordinates allocated to each postcode record.
Easting
Distance in metres east of National Grid origin.
Northing
Distance in metres north of National Grid origin.
Country code
Code used by the Office for National Statistics (ONS) to identify the country in which the Code-Point Open georeferenced coordinates lies.
NHS regional health authority code
English Pan Strategic Health Authority in which Code-Point Location Coordinate (CPLC) falls.
NHS health authority code
English Strategic Health Authority or Scottish Health Board in which CPLC falls.
Administrative county code*
County in which CPLC falls.
Administrative district code*
Unitary Authority, Metropolitan and Non-Metropolitan District, London Borough, or Scottish Council Area in which CPLC falls.
Administrative ward code*
Electoral Ward or Division in which CPLC falls.
10
Within the building of the matched address closest to the postcode mean determined automatically by Ordnance Survey.
20
As above but determined by visual inspection by National Records of Scotland (NRS).
30
Approximate to within 50m of the true position (postcodes relating to developing sites may be within 100m of true position).
40
The mean of the positions of addresses previously matched in PALF but which have subsequently been deleted or recoded (very rarely used).
50
Estimated position based on surrounding postcode coordinates, usually to 100m resolution, but 10m in Scotland.
60
Postcode sector mean.
90
No coordinates available.
GeoPackage is an open, standard, platform-independent, portable, self-describing, compact format for transferring geospatial information. For more information on this format, please see the Getting started with GeoPackag guide.
The following tables give a comparison between the CSV attributes and the GeoPackage attribution:
Those fields containing text (A) will be enclosed by double quotes which have not been included in the sizes listed in the table above. An asterisk (*) denotes variable length.
Fields with null data will appear as "" for text and 0 for numeric.
Each record will be terminated with a carriage return character (ASCII 13) and a line feed character (ASCII 10).
Example of a Code-Point Open CSV record:
"SO16 0AS",10,437292,115542,"E92000001","E19000002","E18000009","E10000014","E07000093","E05012936"
Note that there are no Eastings or Northings in GeoPackage; the geometry is already created in the GeoPackage container and is not listed as data but will be seen as a column in a database (PostGIS) called geometry with a coordinate reference system of British National Grid
EPSG: 27700 for Great Britain (GB) postcodes.
Fields with a null value will appear as [Null] for text (PostGIS) or as an empty field in a GIS. A null numeric value will appear as 0 in both a database and an attribute table in a GIS.
Example of a Code-Point Open GeoPackage record taken from the Information tool in QGIS:
Mnemonic
Description
Data type
Size
N/A
N/A
N/A
N/A
PC
Postcode
A8
8
PQ
Positional_quality_indicator
I2
2
EA
Eastings
I6
*
NO
Northings
I7
*
CY
Country_code
A9
9
RH
NHS_regional_HA_code
A9
9
LH
NHS_HA_code
A9
9
CC
Admin_county_code
A9
9
DC
Admin_district_code
A9
9
WC
Admin_ward_code
A9
9
Description
Data type
fid
int
postcode
TEXT
positional_quality_indicator
int
N/A
N/A
country_code
TEXT
nhs_regional_ha_code
TEXT
nhs_ha_code
TEXT
admin_county_code
TEXT
admin_district_code
TEXT
admin_ward_code
TEXT