Foreign letters. 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.
Litteras estranier. Le litteras debe esser valide in le lingua a parlar. Per exemplo, “ж” es un littera in le alphabeto russe ma non es jammais usate in anglese e dunque non deberea jammais apparer in alcun texto fonte anglese.