You can use keywords listed here in Grasshopper.Plugin.BasicFormatter version 1.3.0.102 and above.
%row.begin% Begins row output %row.end% Ends row output %author% Commit author %date% Commit date %date.day% Date.Day %date.dayofweek% Date.DayOfWeek %date.dayofyear% Date.DayOfYear %date.hour% Date.Hour %date.milisecond% Date.Millisecond %date.minute% Date.Minute %date.month% Date.Month %date.second% Date.Second %date.ticks% Date.Ticks %date.timeofday% Date.TimeOfDay %date.year% Date.Year %date.longdate% Date.LongDateString %date.longtime% Date.LongTimeString %date.shortdate% Date.ShortDateString %date.shorttime% Date.ShortTimeString %message% Commit message %revision% Revision %notes% Notes entered for entry in Grasshopper %parity.string% Returns row parity as string: "even" or "odd" %parity.int% Returns row parity as int: 1 for even; otherwise 0