public List <HistoryEntry> Filter(HistoryList hl) { if (Lastdockflag) { return(hl.FilterToLastDock()); } else if (Startendflag) { return(hl.FilterStartEnd()); } else if (MaximumNumberOfItems.HasValue) { return(hl.FilterByNumber(MaximumNumberOfItems.Value)); } else if (MaximumDataAge.HasValue) { return(hl.FilterByDate(MaximumDataAge.Value)); } else { return(hl.LastFirst); } }