Metadata
Addresses come in many forms. Multiple addresses can describe the same addressable object, and each of those addresses can have a different intended use. A postal address can be different from a location address, and the distinction between them can mean life or death if you use the wrong version when emergency response vehicles must get to an address quickly. Without metadata to understand the address, determining suitability for use can be difficult at best.
Existing national and international standards and guidelines regarding metadata are mentioned in the reviewed standards, including ISO 19115:2003, Geographic information - Metadata, ISO 19139:2007, Geographic information – Metadata – XML schema implementation, the INSPIRE Metadata Implementing Rules, Regulation 1205/2008/EC, and the Federal Content Standard for Digital Geospatial Metadata (USA). Where not specifically mentioned, the metadata are accounted for through code lists/enumerations, dictionary elements, attributes, and registries of information. Not all mentions of metadata are with regards to addresses specifically, but also include geospatial data in general such as positional accuracy of the location address, temporal information, modification, and exchange information for the dataset, including copyright information, data lineage, use restrictions, contact information and a description of the geographic area that the data represents.
Addresses can have numerous incarnations and metadata must be included to determine proper use. Vintage, accuracy, use constraints, and coverage also are important elements in address list use. Metadata components from ISO 19115 and ISO 19139 should be incorporated in at least the dataset level, but additional metadata should be defined at the individual address and addressable object level for guidance. Whilst many of the standards examined had some form of metadata, there is no real measure of consistency across them that would make defining a minimum set of metadata elements necessarily acceptable for an international standard. National bodies maintaining address data could conceivably comply with a metadata standard for data exchange, which is very different from collecting and maintaining it at the individual address level internally.