[Newbies] [Q] Best way of know when a object was added to the image

[Edgar J. De Cleene]

I just "discover" Object DNU timeStamp.

I ask this because

loadKnowPackages
"UCodeLoader loadKnowPackages"
| obj  loader req |
    loader _ CodeLoader new.
    loader baseURL: 'ftp.squeak.org/various_images/SqueakLight/SLupdates/'.
        
        req := loader createRequestFor: 'KnowPackages.obz' in:  HTTPLoader
default..
        
    obj := loader readObject: req.
 
KnowPackages := obj

knowPackages
^KnowPackages

How I could know if  KnowPackages is older as the file on the server ?

For curiosity, how we could know the "age" of all objects in the image ?

Edgar