4. Appendices
1.3 Who supplies Eircode?
Eircode (the company), part of Capita Business Support Services (Ireland) Ltd, is the Postcode Management Licence Holder (PMLH) and were awarded the government licence to design, launch and manage a postcode system for Ireland. This included the design and assignment of the postcode – now called “Eircode”.
This Eircode data is available to external organisations in two forms: a basic version Eircode Address File (ECAF) and a richer version with more data elements Eircode Address Database (ECAD) which is described in this document.
Software applications are available from third party suppliers who provide a variety of products and services using Eircode data.
Find out more about the range of products and services available www.eircode.ie 1.4 Sources of Data
The source data is supplied by the following:
Alias information: Eircode
Administrative information: Ordnance Survey Ireland via https://data.gov.ie
All Other Information: An Post GeoDirectory Limited, which sources information from Ordnance Survey Ireland, the Placenames Branch (Department of Arts, Heritage and the Gaeltacht) and the Universal Service Provider for postal services in Ireland, An Post.
1.5 Addressing in Ireland
Ireland has a number of unique challenges when it comes to addressing. Firstly, people in the same street, townland, apartment building, etc. may write their addresses in very different ways. This arises for reasons of; local common naming conventions, historical reasons, variations in spelling (notably anglicised versions of Gaelic names) and vanity addressing.
An Post, the Universal Service Provider, has prompted postal users to use the addressing format required to maximise the effectiveness and efficiency of the postal service. Their addressing guides comply with the Universal Postal Union’s (UPU) (the United Nations body responsible for promoting standards in the postal industry across the World) addressing guidelines. The postal address as defined by Irish Standard - I.S. EN 14142-1:2011 (Postal services. Address databases), as operated by the Universal Service Provider, An Post,, is the format used in the ECAD.
However, the various ways that people record their own address may differ from the Postal Address. The following examples of the same address and the different ways in which it can be recorded illustrate the problem.
Example:
42 Woodbrook Glen 42 Woodbrook Glen 42 Woodbrook Glen
Diswellstown Rd Riverwood Road Carpenterstown
Clonsilla Castleknock Dublin 15
Dublin 15 Dublin 15
In 2.1 we discuss how alias information available in the ECAD can be used to mitigate this problem. 2.3 describes how the allocation of Eircodes to addresses follows a methodology designed to optimise address verification.
Ireland has a very high level of non-unique addresses (NUA), i.e. the address does not contain a unique building number or name. Approximately 35% of all Irish addresses are non-unique which equates to 600,000 addresses.
The typical example of NUA addressing is where every address in a townland is the same.
The way that post is delivered is by local knowledge of postal delivery personnel of which addressee lives in which house.
N.B. For a NUA address, it is impossible to match to a unique record in the ECAD and assign an Eircode.
We can clearly see the issue below where four separate houses in a townland have the same address, but a different Eircode. Knowing the address isn’t sufficient information to determine the Eircode.
Address 1 Address 2 Address 3 Address 4
Ballinroamin Ballinroamin Ballinroamin Ballinroamin
Holycross Holycross Holycross Holycross
Tipperary Tipperary Tipperary Tipperary
A65 TF12 A65 DE34 A65 TA33 A65 HN88
1.6 Eircode Structure and Presentation
An Eircode is a seven-character postcode consisting of two elements:
1. Three-character Routing Key 2. Four-character Unique Identifier
1.6.1 Recommendations for Storage and Presentation
An Eircode should always be stored as a single string of seven upper case characters in IT systems, i.e. A65F4E2.
An Eircode should always be presented in upper case as two parts separated by a space, on stationary, mail items, computer forms, etc. i.e. A65 F4E2 and never A65F4E2.
1.6.2 Routing Key
The Routing Key is the first part of an Eircode and is consistently three characters long. The Universal Service Provider identified principal post towns through which mail is distributed and Eircode assigned Routing Key codes to those principal post towns. The Routing Key format is Letter-Number-Number with the single exception of D6W for the Dublin 6W postal district.
The existing Dublin Postal Districts 1 to 24 have been retained as D01 to D24. The Routing Key letter and numbers assigned to the remainder of the 139 Routing Keys are not directly linked to counties, towns or any other geographic boundaries. A Routing Key will be shared by many properties in an area. Routing keys are fixed once assigned to an address and do not change.
1.6.3 Unique Identifier
The Unique Identifier is the second part of an Eircode and consistently comprises four characters. The Unique Identifier is unique within each Routing Key, but not across Routing Keys. Unique Identifiers are not assigned in any sequence order, nor is there any hierarchical grouping information contained in the Unique Identifier. Unique Identifiers are fixed once generated for an Eircode, and are only retired if there is a change of building use, e.g. A Georgian House is converted into a block of apartments.
The Unique Identifier has the same allowable characters in each position, twenty five characters in total defined from the following available list of numbers and letters:
6
Routing Key Unique Identifier
NUMBERS: 0,1,2,3,4,5,6,7,8,9
LETTERS: A,C,D,E,F,H,K,N,P,R,T,V,W,X,Y
This provides 25 x 25 x 25 x 25 possible combinations, which allows a maximum of 390,625 Eircodes per Routing Key.
1.6.4 Character Set
The characters allowed in each position in an Eircode are as below:
Component Position Allowed Characters
Routing Key 1 A,C,D,E,F,H,K,N,P,R,T,V,W,X,Y
2 0-9
3 0-9 with the exception of W for D6W Unique Identifier 4 0-9 and A,C,D,E,F,H,K,N,P,R,T,V,W,X,Y
5 6 7
1.7 Eircode Address Database (ECAD)
The ECAF contains the base reference data for over 2 million Irish addresses and is a prerequisite to the purchase of the ECAD. The ECAD contains additional data for each address. For ease of use the two products are delivered in a relational database. The ECAD contains no software; the data within it must be processed for use in IT applications.
The ECAD is comprised of a number of database tables. The tables are divided into a number of categories based on the role they perform within the database. The categories are:
Address – Contains the information that is used to make up an address
Alias – Provides information on address alias information
Lookup – Contains lookup information that has been normalised into separate tables
Information – Holds non address information related to the Address Tables
History – Provides detail of retired address records and their related Eircodes
The tables in the ECAD are described in more detail below (detailed table definition for each table is available in Appendix 1.)
1.7.1 Address Tables
The following is the list of tables that contain the address information stored in the ECAD:
Address Group Address Table
Premises Tables ORGANISATION
SUB_ADDRESS_POINT ADDRESS_POINT BUILDINGS
Thoroughfare Tables BUILDING_GROUP THOROUGHFARE Locality Tables LOCALITY
POST_TOWN COUNTY
Address POSTAL_ADDRESS
GEOGRAPHIC_ADDRESS
The address information stored in these tables is stored in upper case only for English and Irish versions of the address element. Provision has been made to receive Official Irish language versions (Type 3 and 4) in the future, which uses mixed case for Irish versions of the address where required. Address elements always have an associated address type that is stored in the ADDRESS_TYPE Lookup Table.
Address
The Entity Relationship Diagram for Address Tables is shown below, and the tables are described in the following sections.
BUILDING
A record in the BUILDING table generally refers to a permanent physical building, however some records may refer to other entities, e.g. a halting site bay. The BUILDING table is the central hub of the Address Tables, defining the thoroughfare and locality elements of a building. A locality may cross county boundaries, or a thoroughfare may cross multiple post towns, therefore the post town or county information resides solely at the building level.
ADDRESS TYPE Description Single Occupancy
Residential Building
This type of building contains one residential address.
Multi Occupancy Residential Building
This type of building contains multiple residential addresses.
Single Occupancy Non-Residential Building
This type of building contains one non-residential address (business, club or other organisation).
Multi Occupancy Non-Residential Building
This type of building contains multiple non-residential addresses (business, club or other organisation).
Multi Occupancy Mixed Use Building
This type of building contains multiple residential and non-residential addresses.
Buildings can also have a more specific address types such as a Hospital, School, Shopping Centre, etc.
BUILDING_GEOGRAPHIC
There is a one-to-one relationship between the BUILDING_GEOGRAPHIC table and the BUILDING table, joining on BUILDING_ID. The BUILDING_GEOGRAPHIC effectively contains replacement values for the BUILDING table if you wish to create GEOGRAPHIC addresses rather than POSTAL addresses.
ADDRESS_POINT
An address point record exists for every unique address within a building. A standard residential property will have one address point. Apartment buildings and multi-unit commercial buildings will have one address point for every unique address within the building.
Eircodes are assigned at the address point level and reside in the ADDRESS_POINT table.
There are a number of address points that do not have an associated Eircode. The primary reason is some buildings do not receive a direct delivery of mail by the Universal Service Provider. In these cases mail is generally delivered centrally and distributed to each building by internal mail processes, e.g. a University Campus.
For an Eircode to be assigned, a building must receive a direct delivery of post, have a Routing Key, and a verified coordinate. When the BUILDING table STATUS field has a value of 2 this indicates the building does not get a direct delivery of post. Buildings without a Routing Key have STATUS = 3. If a building has a STATUS = 1 but does not have a verified coordinate then no Eircode is assigned. Only addresses with Eircodes are included in the Postal Address table. It is expected, but not guaranteed, that addresses in a STATUS=1 or 3 building that do not receive an Eircode in the release they are introduced would be updated in the next release with the required information to assign an Eircode.
Address points can be one of the following address types:
ADDRESS TYPE Description
Residential Address Point This type of address point has one residential addresses associated with it.
Non-Residential Address Point This type of address point has one or more non-residential address (business, club or other organisation) associated with it.
Mixed Address Point This is a special case where the residential and non residential addresses in the building are essentially the same address. The typical example is a farm house on an active farm.
It is important to note that this is a special case. In general a building with both residential and non-residential addresses (e.g. an apartment over a shop) will receive two address points, one commercial and one residential, and hence two Eircodes.
Buildings can contain multiple address points of type Residential and/or Non-Residential.
SUB_ADDRESS_POINT
A sub address point is an address within a building that has no underlying address information.
This information indicates that there are multiple flats within a building without discrete addresses (e.g. without Flat 1, Flat 2, etc. indicators). These records are inserted into the SUB_ADDRESS_POINT table to indicate their existence. The address point associated with the records is generally of type Residential Address Point, but can also be associated with type Non-Residential Address Point. The SUB_ADDRESS_POINT records are never used to generate a Postal Address and can be ignored for most purposes.
If a building had one postal address and 5 sub address points, there would be five records in table SUB_ADDRESS_POINT and each would have the ADDRESS_POINT_ID of the parent address point, ie. The one associated with the postal address.
ORGANISATION
The ORGANISATION table contains a record for every non-residential address in the ECAD.
The organisation name is present unless the address is vacant or the organisation name is unknown in the case of organisations associated with Non-Residential Address Point. For Mixed Address Points, there is always a reference in the Organisation table and the organisation name is always null.
BUILDING_GROUP
A building group is a collection of buildings with a collective name, located on or near the same thoroughfare.
Building groups can be one of the following generic address types:
ADDRESS TYPE Description
Residential Building Group This type of building group contains buildings with residential addresses only.
Non-Residential Building Group This type of building group contains buildings with non-residential addresses (business, club or other organisation) only.
Mixed Building Group This type of building group contains buildings with residential and non-residential addresses.
Building groups can also have a more specific address type such as a Hospital, School, Shopping Centre, etc.
THOROUGHFARE
Thoroughfares generally refer to the street, road, avenue, etc. on which a building resides.
The BUILDINGS table has a reference to both PRIMARY and SECONDARY thoroughfares (if populated), which both reference this THOROUGHFARE table.
LOCALITY
A locality refers to areas, districts, towns, etc. and is generally one of the following address types:
ADDRESS TYPE Description
Rural Locality This is generally a townland.
Industrial Estate Industrial Estate, Industrial Park, Business Campus, etc.
Shopping District Shopping Centre.
Housing Estate Residential Housing Estate.
Village Based on Census 2011 population < 1,500.
Town Based on Census 2011 population > 1,500.
Urban Area Wholly within a village/town/city e.g.
Rathmines.
Suburban Locality This is an area that is both rural and urban, as it is both a townland, and also an area name applied to houses in a town, as the town has extended partially into the townland.
The BUILDINGS table has a reference to PRIMARY and SECONDARY localities (if populated), which all reference this LOCALITY table.
All records in the POST_TOWN table are duplicated in the LOCALITY table, where the LOCALITY_ID in the LOCALITY table is equal to the POST_TOWN_ID in the POST_TOWN table. These LOCALITY records have one of the following address types:
ADDRESS TYPE Description
Village Based on Census 2011 population < 1,500 Town Based on Census 2011 population > 1,500
Postal District Dublin 1 to 24
City Dublin, Cork, Limerick, Galway or Waterford
POST_TOWN
The POST_TOWN table contains a record for every post town in the ECAD. The post town is a significant element of the Postal Address, however it is not always populated in an address.
The official post office guide, Eolaí an Phoist1, describes post towns in the following manner;
“A provincial postal address may include the name of a town or village several miles distant, with which the addressee has little or no connection, and, in some places, especially if this residence happens to be near a county boundary, the name of the neighbouring county instead of the county in which he actually resides. The explanation is that the main mail despatches have to be sent for more detailed sub division to certain centres known as POST TOWNS, chosen because of their accessibility and convenience.”
The POST TOWN record always has an address type of post town.
COUNTY
The COUNTY table contains a row for each of the 26 counties in Ireland.
A COUNTY record always has an address type of County.
1 Ireland. Eolaí an phoist: Post office guide. Dublin
POSTAL_ADDRESS
The POSTAL ADDRESS Table contains a row for every Postal Address in the ECAD. It contains the following fields:
POSTAL_ADDRESS field
An ECAD_ID referred to in the POSTAL_ADDRESS table is either the ORGANISATION_ID if it is not Null, or the ADDRESS_POINT_ID which is never Null. ECAD_ID is simply a generic name that covers all of the primary keys in the address tables (ORGANISATION_ID,
ADDRESS_POINT_ID, BUILDING_ID, BUILDING_GROUP_ID, etc.) and allows joining to the various _INFO table.
You don’t join the ECAD_ID in the POSTAL_ADDRESS table to any of the _INFO tables, you use the appropriate ID. For example to get coordinates you join to the SPATIAL_INFO table on POSTAL_ADDRESS.BUILDING_ID = SPATIAL_INFO.ECAD_ID.
The individual address elements (i.e. BUILDING_ID, THOROUGHFARE_ID, etc.) make up the address lines. Some address elements are combined for an address line (e.g. Building Number and Thoroughfare Name). Address creation rules have been applied to create Address Line 1-8 in both English and Irish. The final line in every Postal Address in the table is the Eircode. For inbound international mail the country name IRELAND should be appended as the last line of the Postal Address.
The NUA field contains a Y value when the address is a non-unique address, and N when it is a unique address.
The GAELTACHT field contains a Y value when the address is in a Gaeltacht area, and N when it is isn’t.
The ADDRESS_REFERENCE is the An Post GeoDirectory address reference identifier used by the Universal Service Provider.
GEOGRAPHIC_ADDRESS
The GEOGRAPHIC ADDRESS Table contains a row for every Geographic Address in the ECAD. It contains the following fields:
GEOGRAPHIC_ADDRESS field
ADDR_LINE_5
ECAD_ID is simply a generic name that covers all of the primary keys in the address tables (ORGANISATION_ID, ADDRESS_POINT_ID, BUILDING_ID, BUILDING_GROUP_ID, etc.) and allows joining to the various _INFO table.
You don’t join the ECAD_ID in the GEOGRAPHIC _ADDRESS table to any of the _INFO tables, you use the appropriate ID. For example to get coordinates you join to the SPATIAL_INFO table on POSTAL_ADDRESS.BUILDING_ID = SPATIAL_INFO.ECAD_ID.
The individual address elements (i.e. BUILDING_ID, THOROUGHFARE_ID, etc.) make up the address lines. Some address elements are combined for an address line (e.g. Building Number and Thoroughfare Name). Address creation rules have been applied to create Address Line 1-8 in both English and Irish. The final line in every Geographic Address in the table is the Eircode.
The NUA field contains a Y value when the address is a non-unique address, and N when it is a unique address.
The GAELTACHT field contains a Y value when the address is in a Gaeltacht area, and N when it is isn’t.
The ADDRESS_REFERENCE is the An Post GeoDirectory address reference identifier used by the Universal Service Provider.
1.7.2 Lookup Tables
The Lookup Tables are used to tie together the Address Tables. They have been created when the Address Tables were normalised. The Lookup Tables are as follows:
ADDRESS_TYPE
BUILDING_TYPE
DESCRIPTOR
GEOGRAPHIC
QUALIFIER
IRISH_VERIFICATION
ROUTING_KEY
GEODIRECTORY_LOOKUP ADDRESS_TYPE
This table contains one record for each Address Type. Address Types categorise addresses.
The address type is a field in every Address Table and thus allows for addresses to be consistently queried.
For example a BUILDING, a BUILDING GROUP or a LOCALITY may all have an Address Type of “Industrial Estate”. The Address Type of a BUILDING has a bearing on what other information is available for an address. For example if a building has an address type of SINGLE OCCUPANCY RESIDENTIAL BUILDING this means that there will be no entries in the ORGANISATION table for that building. All Address Tables contain an ADDRESS_TYPE_ID that references the ADDRESS_TYPE table.
BUILDING_TYPE
The BUILDING_TYPE table contains one record for each building type, e.g. Detached, Terraced, etc. The BUILDING_INFO table contains a BUILDING_TYPE_ID that references the BUILDING_TYPE table.
DESCRIPTOR
This table contains one record for each Descriptor. A Descriptor is the part of a thoroughfare
This table contains one record for each Descriptor. A Descriptor is the part of a thoroughfare