Windows 2003 Schema USN Number

Hi all, I am facing a problem with my windows ad schema. When I opne adsiedit.msc and open the properties of the schema, the changed time is getting changed daily at 12.15 AM. is it the default behaviour or anything going wrong?

And also I woud like to see the USN number of the schema, objects and GP Objects. For that is there any way to export that to a xls file?

Please help me in this regard