RIght now there is no revert feature. However, the next time a computer runs an inventory scan it will be added back into management suite.
You could have a barcode form kick off an archive by creating a group and putting the archive rule in a group then have the barcode web rule kick off the group.
What if it does not reappear? I have been archiving units and came across a device in our Solar winds that was pulling traffic. I scanned the segment with UDD but did not find it, then I checked in Asset control and sure enough it was still there. The UDD scan did not include it because it was already in asset manager and yet since the unit either did not have the agent anymore or simply did not get connected to the network during a scan period, it fell through the cracks.
I am reluctant to archive machiens of prior employees in case months from now they are reallocated and not discovered.
As far as I know, UDD doesn't check the Asset Control database to see if a device is unmanaged or not. Most likely the device ended up somehow already in a deployment task and can be found under the Pending Unmanaged Client Deployments (Network view - Configuration). As a backup-plan, you can also use Database Doctor to export the devices first to .scn files before moving them to Asset Control. That way you still have a scn file you can copy to LDSCAN to be picked up by the Inventory Server Service again.