Sub-building indicators are text strings which indicate routing within a building/delivery point. Postal addressing for delivery is usually defined to the point of delivery, usually the door of a building. Sub-building indicators, such as "floor", "apartment", "level", "staircase" and "flat" allow recipients (and, in some cases, postal services) to define delivery beyond the building level.
Practical International Data Management Online. A free resource from GRC Data Intelligence. For comments, questions or feedback: email@example.com