pear calendar

hello again! sorry, but I have yet another question. This time about pear calendar. I've found out about how if you define CALENDAR_ENGINE to PearDate, you can go before 1970 or after 2038 in dates. So I tried it and it works beautifully; but I seem to have oen problem, which I think (not positive but might) be related to doing this. I want to use the adjust method for when a date is invalid; and it makes my coding a little easier when I go to a previous or next month. However I have noticed that this isn't always accurate. for instance if I go from january 2004 to December 2003 (with month 0 year 2004), the end day of december 2003 is a few days before the beginning day of january. according to the calendar jan 1 is on a Thursday, and then I use adjust with the invalid date month 0 of 2004, it says that dec 31 is on Monday. If I just enter month 12 of 2003 it works fine, though. I thought this might be because, well, I don't think using the PearDate option uses timestamps, does it? does adjust rely on these timestamps to fix the problem? I may be way off course here, but it is a guess. Second question is a curiosity. How far back or ahead can it go with use PearDate in that definition? I have gone pretty far back and it has not complained...though it does have a problem with leap years before year 1000 :)!!!! not that that should be of any major worry... but should it be able to go back to year 1 CE? It hasn't complained when I tried, but, well, just curious.