iSeries - Library Change Date

Could someone tell me what the "Change Date/Time" signifies for a Library Object on the iSeries?  For example: I have a library named Library1. If I look at the attributes for that library object, it shows that the last change date/time was Today...even though I know that the object itself hasn't changed.

Does this attribute reflect that an object within the library has changed...or is it telling me that the actual library object has changed somehow...even though I know that no changes were made to it?

I just wanted to better understand what this might mean...

I appreciate any guidance...