ok here is how clips work
Inside a clip you have blobs (binary large objects) this represents your file or part of your file.
When you archive without collections each items is stored as a blob on centera
When you archive with collections many files are rolled into a c-clip (up to a max of 10MB) then the c-clip is stored on centera
When you do a delete without collections the item is deleted from Centera
if you do a delete with collections the c-clip and all it's contents remain on the centera until all items in the c-clip are marked for deletion. Then and only then is the c-clip and all data within the c-clip deleted
Example
File created in 2002 and a file created in 2009 are archived at the same time and both end up in the same c-clip
If you delete file from 2002, the reference for the item will be erased in EV but the actual data will remain on the centera.
Now you decide to delete the file from 2009. Since the file for 2009 and the file from 2002 are the only two files in the c-clip then the whole c-clip is deleted from the centera because all items contained within the c-clip have been marked for deletion
How this works will also depend on which version of centera you have
Basic
Compliance
Compliance Plus
Each version has different ways to enforce compliance retention