scope:

This standard provides a dictionary of the possible5) components of postal addresses, together with examples of and constraints on their use. This standard This standard defines three hierarchical levels of postal address component: segments, such as addressee specification, which correspond to major logical portions of a postal address; constructs, such as organisation identification, which group elements within segments into units which are meaningful for human interpretation; elements, such as organisation name or legal status, which correspond to the lowest level of constructs, i.e. those which are not themselves made up of subordinate elements, though they may be sub-divided for technical purposes. To cover multiple occurrences and locations of elements in an address, and to be able where necessary to work with sub-divisions of element content, the standard defines a fourth level: element sub-types, such as door type or door indicator, representing parts of conceptual elements, such as door, for database storage or to facilitate presentation, or representing multiple instances of conceptual elements for use in defining address element structures or templates.