Tom Nook Addressing System

The Tom Nook Addressing System is a 20-character, alphanumeric code used to identify gamers such as Nintendo gamers. The main focus of this identification system is to make all players handle within one direction and this identification system prevents memory problems or malicious attacks when the gamer plays the game.

The system is run by Tom Nook, a special character who played the important role in almost all of the Animal Crossing series.

The system was introduced on 24 September 2004, the same date when Animal Crossing was released in Europe. Initially restricted to Animal Crossing gamers, it was later expanded to cover Mario gamers, Sonic gamers in early 2007, and to all games in late 2009.

The ID is only given to a gamer when a gamer adds a username or a Nintendo Network ID to the official website of Tom Nook (http://www.tomnookofficial.com).

Structure
The Tom Nook Addressing System consists of 20 characters, with the first three relate to the username.
 * The first consonant or a number in a username or the Nintendo Network ID and the first vowel (if there is no vowel in the username, X is used);
 * The last character (either a letter or a number) in a username or the Nintendo Network ID;
 * A combination of six numbers representing the date of birth (two digits for the day, two digits for month, two digits for year);
 * A gender indicator (M for Male, F for Female, if not telling, X is used in the gender position)
 * A two letter local memory tag representing issuer;
 * A three-letter sequence indicating the month of registration (e.g. APR = April);
 * A two number age identifier indicating the user's year of registration - uses the last two digits of the year;
 * A three-letter sequence used to distinguish the gamer with the same first 16 characters (letters I and Q are not included);
 * A checksum, calculated over the first 19 characters for error detection

Validation
See Tom Nook Addressing System/Validation on how to validate Tom Nook Addressing System numbers.

Exceptions
There are several exceptions exist, including:

".", "?", "!", "" and other punctuation marks or symbols
If any step in the procedure leads to ".", "?", "!", "" or any other symbol appearing anywhere in Tom Nook Addressing System, the punctuation symbols or other symbols are replaced by letter "X".

Offensive combinations
To prevent three character combinations at the beginning of the Tom Nook Addressing System forming a foul-sounding word (such as profanity), a list of inappropriate words lists many offensive three-letter combinations (such as SUX or PEE) that provide replacements: the second vowel of the username is replaced with "X". Same applies to the three-letter sequence before the checksum.

Local memory tags
This is a list of local memory tags used in Tom Nook Addressing System. Note that I, O, Q, U and Z are excluded: I is too similar to number 1, O and Q are too similar to number 0, U is too similar to letter V and Z can be only used elsewhere. T is not used as the first letter of the local memory tag.

Example
An example of the Tom Nook's ID number in Tom Nook Addressing System format is TOK300500MAASEP02RLV9.