Altiris Inventory Solution - Where it get inventory information?

I have a PC with MS Office 2010 and later upgraded with Office 2013.

However, i still found Office 2010 in "Add / Remove Program" after the upgrade.

so i uninstall Office 2010 and leaving only Office 2013 in the PC.

And after all, i can only see Office 2013 in "Add / Remove Program"

However, when i scan inventory with Inventory Solution, it said both Office 2010 and Office 2013 are installed, even i purge the PC object in NS and do it all over again.

So where does Inventory Solution get the software inventory info.?