Mapcodes can be easily translated between several different alphabets.
The default system is based on the roman alphabet. Mapcodes in other alphabets are generated by character substitution.
The substitutions were chosen carefully:
mapcodes must be easy to read and write.
Characters were chosen that have few "strokes", and no accents.
mapcodes must be easy to read aloud and communicate.
Characters were chosen that are short and easy to pronounce (in the sense that the roman letter "B" is shorter and easier to pronounce than the roman letter "W").
Furthermore, characters were chosen that sound as different as possible from all other chosen characters.
mapcodes must be easy to type
Whenever possible, characters were chosen that do not require Shift or other special keys to access on a standard computer keyboard.
mapcode characters must be easy to recognise and distinguish
Characters were chosen that look as simple as possible, and look as different as possible from all other chosen characters.
mapcodes must not look like normal language
Whenever possible, vowels are excluded.
mapcodes must remain unambiguous.
The roman letter H can not easily be distinguished from the greek H (pronounced "eta") or the Cyrillic H (pronounced "n").
Thus, the mapcode HH.HH might be misinterpreted unless these characters are all mapped to the same value.
Furthermore, characters were chosen that look as different as possible from other chosen characters.
Below is the current table of supported alphabets.
Disambiguating all-digit mapcodes
In order to prevent mapcodes from being ambiguous in certain contexts, a special adjustment is made to mapcodes that would otherwise consist only of digits
(and might thus be confused with a number). The last two digits are substituted by a combination of a vowel (A, E or U) and another character (which may also be a vowel).
In alphabets that have less than 24 appropriate characters (such as Greek), a different encoding is chosen instead,
where the first digit of the mapcode is replaced by the vowel A, and the last two digits are replaced by a combination of two characters (each of which may also be the vowel A).