SELECT RIGHT('ФФФ',1) FROM rdb$database

function TIBXSQLVAR.GetCharsetSize: Integer;
begin
  case SQLVar.SQLSubtype and $FF of
    0, 1, 2, 10, 11, 12, 13, 14, 19, 21, 22, 39,
    45, 46, 47, 50, 51, 52, 53, 54, 55, 58 :  Result := 1;
    5, 6, 8, 44, 56, 57, 64 : Result := 2;
    3 :
    begin
      // System Tables incorrectly state they are in Unicode_Fss character set but they are not
      if (POS('RDB$', String(SQLVar.RelName)) = 1) or
         (SQLVar.SqlLen mod 3 <> 0) then
        Result := 1
      else
        Result := 3;
    end;
    // КА Для кодировки UTF-8 (Charset 4) размер составляет 4 байта
    4, 59 : Result := 4;
    else
      Result := 1;
  end;
end;