I'm defining "address" as "a physical location, usually visibly numbered". <b>Numbered</b> was used in the definition to exclude purely geographical features not usually considered to have or need an address. <b>Visibly</b> was used in the definition to exclude entities that might be numerically coded (like census features) but the number is not typically apparent nor used for directional or delivery purposes. <b>Usually</b> was used in the definition because exceptions abound (such [residences in Carmel][1]). Enumerating the possible kinds of addresses resulted in: - buildings. - entire floors of buildings. - apartments/offices/rooms in buildings. - cubicles/mailstops in buildings. - loading docks. - slips on boat docks. - slots in trailer parks. - post office boxes and private mail drops. - military APO/FPO addresses. - jail/prison cells. - campground lots. - outbuildings (not usually visibly numbered, but often desireable in delivery databases). - undeveloped parcels (not usually visibly numbered, but often required in address databases). What other kinds of "physical locations, usually visibly numbered" have I forgotten to include in the above list? Two questionables are: - hospital beds. - cemetary plots. ---------- Update from comments: The enumeration (ie, determining how many codes are necessary) is desired to allow coding address kinds to differentiate records in an address database. Eg, SELECT * FROM ADR WHERE KIND IN (1,3,5). "Usually visually numbered" (alphanumerics are OK) is preferred to just "coded" as described in the original question. If the location isn't visually numbered, it's unlikely to be the target of directions/deliveries, and would not be kept in the address database. Just think of the question as "how many different kinds of places do we number to make directions/deliveries easier?" [1]: http://www.semaphorecorp.com/misc/carmel.html