THE NAC GLOBAL POSTAL CODE SYSTEM

1. If an eight-character NAC represents an area with only one house and without any postal zone borders, then the global postal code of the house is the same as the NAC, for example, NAC: 7HGG KJ9L.

2. If the NAC represents an area with several houses, the global postal code of each house in the area is the NAC plus a locally defined third character string which people can define by themselves using a family name, a location name or a name of their choice. The locally defined third string should employ characters from digits or English capital letters, have at least one vowel other than I or O, not include blank spaces, and be unique in the area, for example, NAC: 7HGG KJ9L DAVID. The requirement of at least one vowel other than I and O is to distinguish the third string from the altitude NAC string which does not include any vowels: A, E, I, O, U, Y. The characters I and O look too similar to 1 and 0; so they are not clear enough to distinguish the locally defined string from the altitude string.

3. If the NAC represents a high-rise building with many apartments, the global postal code for each apartment is the NAC plus a locally defined string named in a way similar to case 2, for example, NAC: HGJK PLLT A509.

4. If a NAC represents an area split by a postal zone border, and a house is located in the larger part of the area, then the global postal code of the house is the NAC or NAC plus a locally defined string; if a house is completely within the smaller part of the area, then its global postal code should be a nine- or ten-character NAC to specify the location of the house more accurately, instead of an eight-character NAC; if a house in the smaller part of the area occupies part of another NAC area called B which belongs to the same postal zone as the house and is not split by any postal zone borders, then the global postal code of the house is the NAC of area B or the NAC of area B plus a locally defined third string.

5. The longitudinal distance of the area represented by an eight-character NAC becomes small when it is close to the poles. For this situation, a seven- or six-character NAC can be used as the global postal code of the area.

6. If a house itself is split by a postal zone border, the global postal code of the house will be a nine- or ten-character NAC representing the location of its main entrance.

Having obtained the global postal code, people can start to include it on a letter as extra information immediately no matter how many post offices have already started sorting mail based on the codes. If some post offices have been sorting mail based on the codes, a letter with a NAC global postal code can be sent faster.

The writing convention of the global postal code on a letter is to write the global postal code on an extra line at the bottom of the current address and domestic postal codes no matter what kind of language and address order are used. For example:

                 Mr. Xinhang Shen
                 1608-45 Huntingdale Blvd
                 Toronto, ON M1W 2N8
                 Canada
                 NAC: 8CNK Q8XM

This writing convention allows post offices to sort mail by either domestic postal codes or NAC global postal codes. Therefore, the domestic postal code systems can be replaced by the NAC global postal code system gradually.

Post offices can use character recognition techniques to read addresses. If the last line of an address starts from NAC, then the following character strings will be processed as a NAC global postal code. One of the algorithms for computers to sort mail based on the NAC global postal code is explained in the following:

If postal services do not want to change anything except the mail sorting software, then the software can be programmed according to the following procedure:

1. Convert the first two character strings of the NAC global postal code into decimal longitude and latitude;
2. Use the city boundary file to check whether the destination is within the city or not;
3. If the destination is within the city, then use the boundary files of the inner city areas to find out the area of the destination and to transport the mail to the post office in charge of the area;
4. If it is not within the city, then use the boundary file of the country to check whether the destination is in the country;
5. If the destination is in the country, use the boundary files of postal zones at the city level to find out the postal zone containing the destination and to transport the mail to the postal terminal in charge of the postal zone;
6. If it is outside the country, then use the boundary files of countries to find out the mail destination country and to transport the mail to the country's postal terminal;

The mail sorting software based on this algorithm can work together with the existing structure of post offices and help sort all mail from the international level to the final address automatically. Moreover, since the current distribution structure of postal corporations are not optimal, this mail sorting program also allows the post offices to adjust their mail transportation routes to send mail more efficiently. For example, Canada Post Corporation may set up more international postal terminals, then other countries can send mail to a specific Canadian postal terminal if the distance from the mail destination to the terminal is the shortest. This adjustment can prevent some situations such as a letter from Seattle to Vancouver being sent through New York City and Toronto and then to Vancouver - an unnecessary long trip which wastes both time and money.

In addition, the NAC global postal code system has many other advantages over current postal code systems:

1. The NAC global postal code is assigned to every mailing address in the world, with much higher resolution than any other postal codes. With a NAC global postal code, a letter can be sorted from the world level to the final address automatically.
2. The code is permanently attached to the area and never changes. This quality can prevent both the user and the post office unnecessary inconvenience, a wasting of time and money and a resulting loss of mail.
3. The NAC global postal code need not be assigned by a post office, which can help people living in newly developed areas to get their postal services immediately.
4. The code can be used instead of the domestic postal code to save costs in revising and publishing postal code books and postal zone atlases periodically.
5. The code can be used for all other services related to addresses such as emergency services, and taxi and delivery services, and in the future, telephone, fax and internet services.
6. The code can be obtained from maps with the NAC grid or by Global Positioning System (GPS) units with the NAC display. It can also be derived from the longitude and latitude coordinates obtained from ordinary maps or measured by other methods.
7. The codes can be used to determine the distance and natural time difference between any two addresses and their relative locations in the world.
8. The code can be directly used in navigation to find addresses or locations by ambulances, trucks, airplanes and individuals equipped with GPS units.
9. The code can help people to pinpoint an address on a map of the NAC grid conveniently in spite of the amount of detail and the scale of the map, which can help people to determine the environment and climate of an address.
10. The code can be easily remembered because of its clear meaning, reasonable length, multiple uses and multiple access.
11. The system is self-motivated. Since the system can start to work immediately parallel to the current domestic postal code systems, it does not need any international agreements to initiate the system. Any country can start to use the system directly when it is ready itself and will receive all the benefits of the system immediately.
12. The code has certain self-error-detecting function. There is more than 80% chance for a computerized mail sorting program to find out a wrong NAC global postal code since a random NAC may represent an area in oceans where no one lives. This property can avoid most mail with wrong codes being sent to wrong places.
13. NAC global postal codes can also help people to understand, interpret and communicate all geographic, geologic, ecological, meteorological, oceanographic, archeological, environmental and astronomic information represented by Natural Area Codes.