This is my solution for representing characters in ternary computer:
Presented system of character coding is intended for 3-trit ternary computer. One character is coded by 3 trits only, so it can code only 27 different combinations and because of that we need some special codes to switch characters sets to cover more characters. Lets take 3 fonts and each of them will have 3 layouts - totally 3^5=243 possible characters. First font covers standard Latin characters, digits and some symbols from ASCII. Second font covers Russian characters (except similar to Latin) and the rest of standard symbols from ASCII. Third font covers pseudo graphics 2x2 "pixels" per character, Greek characters (except similar to Latin and Russian), additional characters to support some European languages (Ukrainian, Belorussian, Serbian, Finnish) and also some mathematical symbols. There are some special codes: SL - switch layout that is available in all fonts and all layouts, SF - switch font that is available in layout N of all fonts, NL - new line that is available in layout N of all fonts, TC - terminal character that is available in layout N of all fonts, and "space" that is also available in layout N of all font. By default we have layout N of the font N. Switch font does shift forward of current font (N->O->P->N etc.) and set current layout to N. Switch layout does shift forward of current layout (N->O->P->N etc.) and keep current font untouched. Terminal character is used as marker of end of text in memory of 3-trit computer.