This would be an extension to llGetInventoryAcquireTime but to get the last time an object's inventory items was updated. Primarily useful for INVENTORY_NOTECARD inventory items.
Currently when a note card is edited within an object the CHANGED_INVENTORY change event is triggered. For an object with multiple control and/or configuration settings note cards there is no easy method to check to see which note card has been updated and possibly needs to be processed. And so instead of just processed the one needed changed note card, all the control/config note cards have to processed in turn.
It would still be up to the script maker to track the update times on the various needed control note cards of course, but having a way to determine which files actually need to be processed and those that can be skipped would help in reducing some load on the servers and speed up internal script updating.
This would also be in Slua for ll.GetInventoryModifiedTime of course.