Letters must be valid in the language being spoken. For example, “ж” is a letter in the Russian alphabet but is never used in English and so should never appear in any English source text.
ⵉⵇⵇⴰⵏ ⴷ ⵉⵙⴽⴽⵉⵍⵏ ⴰⴷ ⵣⵔⵢⵏ ⴳ ⵜⵓⵜⵍⴰⵢⵜ ⵏ ⵡⴰⵡⴰⵍ. ⵙ ⵓⵎⴷⵢⴰ, “ⵘ” ⵉⴳⴰ ⴰⵙⴽⴽⵉⵍ ⵏ ⵜⴼⵉⵏⴰⵖ ⵎⴰⵛⴰ ⵓⵔ ⵍⴰ ⵜ ⵙⴰⵔ ⵏⵙⵙⵎⵔⴰⵙ ⴳ ⵜⵎⴰⵣⵉⵖⵜ ⵜⴰⵏⴰⵡⴰⵢⵜ ⵓⴽⴰⵏ ⵓⵔ ⵉⵅⵚⵚⴰ ⴰⴷ ⵙⴰⵔ ⵢⵓⵎⴰⵏ ⴳ ⵓⵍⴰ ⴽⵔⴰ ⵏ ⵓⴹⵕⵉⵚ ⴰⵙⴰⴳⵎ ⵏ ⵜⵎⴰⵣⵉⵖⵜ.