I can't find a description of what the various variables do. Some are self-explanatory, but what is "current day number"? Is it 0-7 (Sun-Sat)? Or is it 1-365? I'm trying to run a report with date range parameters for a 6 week range Sun-Sat regardless of the day you run it (not a rolling 6 weeks). Thanks.

The CURRENT_DAY_NUMBER is the Day of the Month Number. One option to consider is to use the power of Crystal Reports to derive the 6 week if based on the Current Day. This would relieve a user from having to pick a date range and would also allow the report to be scheduled - which being automated can not prompt a user.