Question about the Acrobat 9.0 Organizer, more precisely the structure of the "Organizer90" sqlite file.

I am not sure if this is the correct forum, but if not please point me towards the correct one. As part of an investigation, we are trying to understand the logging system of Acrobat 9.0 Organizer, more precisely the structure of the "Organizer90" sqlite file. Even more specifically, there are 3 dates that are stored : ModDate, LastViewed, LastOpened. In what situation could the LastViewed value could be set to 0000-00-00 00:00:00 ? Am I looking at the lastViewed and not the lastOpened which can be changed by using the clear history function of the Organizer.

Thank you