User:40bus/Phone numbers/System 2

A System 2 phone number is a ten-character string. The System 2 phone numbers are alphanumeric. They are in the format A1A 1A1 1AA1, where A is a letter and 1 is a digit, with a space separating the third and fourth, as well as sixth and seventh characters.

Area code
An area code is a geographical region in which all postal codes start with the same three characters.

The large populations of both Quebec and Ontario cause both provinces to be subdivided into three and five postal districts, respectively, and each has at least one urban area so populous that it has a dedicated postal district ("H" for the Montreal region, and "M" for Toronto). On the other hand, the low populations in Nunavut and the Northwest Territories (NWT) mean that even after Nunavut separated from the Northwest Territories and became its own territory in 1999, they continue to share a postal district.

The digit identifies the area code as urban or rural. A zero indicates a wide-area rural region (or, in rare instances, a special-purpose code); all other digits indicate urban areas. The second letter represents a specific rural region, an entire medium-sized city, or a section of a major metropolitan area. In the extreme case, some FSAs in downtown Toronto, Montreal, and Vancouver are assigned to individual buildings. Rural FSAs also vary widely in population, with the Northwest Territories' X0G covering only the hamlet of Fort Liard, but adjoining X0E covering every other community in the territory except Yellowknife.

Office code
The next three characters denote an office code. An office code denotes a specific single address or range of addresses, which can correspond to an entire small town, a significant part of a medium-sized town, a single side of a city block in larger cities, a single large building or a portion of a very large one, a single (large) institution such as a university or a hospital, or a business that receives large volumes of mail on a regular basis.

Office codes ending in zero correspond to postal facilities, from post offices and small franchised retail postal outlets all the way up to sortation plants. In urban areas, LDUs may be specific postal carriers' routes. In rural areas where direct door-to-door delivery is not available, an office code can describe a set of post office boxes or a rural route. LDU 9Z9 is used exclusively for Business Reply Mail. In rural FSAs, the first two characters are usually assigned in alphanumerical order by the name of each community.

LDU 9Z0 refers to large regional distribution centre facilities, and is also used as a placeholder, appearing in some regional postmarks such as the "K0H 9Z0" which formerly appeared on purely local mail within the Kingston, Ontario, area.