Conclusions
Address assignment scheme
There is not a single best address assignment scheme that is suitable for all countries.
Therefore it would be better to provide guidelines of good practices for address assignment schemes.
Terminology
Terminology is important for communication about and understanding of addressing. All reviewed address standards include terminology.
Terminology is a minimum requirement in an international address standard.
Conceptual model
The conceptual model describes addressing concepts and relationships between them.
All reviewed address standards include a conceptual model and describe addresses as a combination of components or elements, often comprising a hierarchy. Address classification, either by content (scheme) or by addressable object is a common theme in the reviewed address standards.
A conceptual model should be included in an international address standard. Following terminology, this is the second most important requirement to be included.
Metadata
Metadata is important for the understanding and exchange of address data.
Many of the reviewed address standards define metadata, but it was not possible to identify a minimum set of metadata elements from these.
An international address data standard should make use of existing metadata standards where possible, such as, ISO 19115 Geographic information – Metadata or ISO/IEC 11179 (all parts) Information technology – Metadata registries (MDR). If required, address-specific metadata can also be defined.
Encoding
Encoding specifications for the conceptual model and metadata are required to exchange one or more address data records as data files or electronic messages.
Most of the reviewed address standards include an encoding of the conceptual model.
An international address standard should not specify a new encoding but should facilitate interoperability between existing encodings.
Address data maintenance
Address data maintenance is only relevant when an address dataset is maintained.
Few of the reviewed address standards include specifications for the maintenance of address data.
These specifications cannot be enforced by an international address standard, but can provide guidance to countries or regions that want to implement processes and procedures for address data maintenance.
Quality management refers to the procedures and measures for the development, maintenance and communication of the quality of an address.
Some of the reviewed address standards include quality management, such as, attribute accuracy, logical consistency, completeness, positional accuracy and temporal accuracy.
An international address standard should make use of existing quality standards, such as, ISO 19157 Geographic information – Data quality and ISO 19158, Geographic information – Quality assurance of data supply. If required, address-specific quality management can be defined.
Life cycle tracks the temporal phases, status, and versions of an address.
In the reviewed address standards there is consistency in the requirement to track the life cycle of an address record in the database and, more importantly, of the address in the physical world.
Life cycle elements and a life cycle schema should be included in an international address standard.
Address aliases, such as multilingual addresses, abbreviations in the address or alternative addresses for the same addressable object, are used on a daily basis all over the world.
Many of the reviewed address standards support address aliases.
An international address standard should include support for address aliases in the conceptual model.
A definitive address dataset is one of the ultimate goals of an address standard.
However, definitive address datasets were not applicable in most of the address standards reviewed, possibly because custodians were not identified or addressing is decentralised within a country.
There is not enough of a body of known definitive address datasets for inclusion in an international address standard.
Address rendering
Standardizing address rendering streamlines mail production and processing, but there are also benefits for the use and display of addresses on maps, handheld devices, etc.
Some of the reviewed postal address standards include rendering rules. None of the reviewed non-postal standards include address rendering rules for maps and handheld devices, constituting a potential gap.
An international address standard should include specifications for address rendering.
Standardization guidance for national address infrastructures
From the review of the address standards, one can conclude that the following standards are important for a national address infrastructure:
- A standard for each address assignment scheme in use in the country, including the components and how values are assigned to them. This does not imply that there is a single address assignment scheme in use, but rather that the schemes and their areas of jurisdiction are described in a standard. Refer to AS/NZS 4819 and SANS 1883 as an example.
- A standard for address data that can be used by producers and custodians to aggregate and maintain address data. Such a standard should include metadata, quality management, life cycle and address aliases. Refer to US FGDC as an example.
- A standard for the transfer and exchange of address data in electronic form. This exchange could happen between users and producers of address data, or between different users of address data. The electronic form or encoding of address data should be compliant with the standardized address assignment schemes. Refer to the XML schema in US FGDC and AS 4590.
- A standard by the postal operator with specifications for the rendering of address labels on mail items. The components used in the address rendering should be compliant with the standardized address assignment schemes (refer to 1. above), but might have to be extended with components for postal purposes, such as a postcode or postal delivery service. Refer to AFNOR XP Z10-11 as an example and the standard by New Zealand Post (2006).