[lmikle]

Угу, только немного геморойнее.
А через множества, оно мож и не совсем оптимально, зато красиво и читабельно:

Код:

type
  TSelectedDayOfWeek = (sdwMonday, sdwTuesday, sdwWenesday, sdwThirsday, sdwFriday, sdwSaturday, sdwSunday);
  TSetOfSelectedDayOfWeek = Set Of SelectedDayOfWeek;

var
  Days : TSetOfSelectedDayOfWeek;
begin
  Days := [sdwMonday, sdwSaturday, sdwSunday];
  Days := Days + [sdwTuesday];
  Days := Days - [sdwMonday];
end;