My few cents
When they say the application has received a POSITIVE FINAL DETERMINATION FOR ELIGIBILITY, they say the application is very much fine to proceed to process. Here, The Process means background, security and medical checks

. We clearly know a PER means, an application corresponds to the MI, 6 selection factors, 67 points etc., So, after all these, the VO has just to confirm the documentation is genuine using background checks and then proceed to the security and medicals.
Note: CIO officers will only make negative selection decisions. Applications that meet the pass mark are forwarded to a visa office. The visa officer will review the application and case analysis provided by the CIO and make the selection decision.
The reason for the above note is the CIO cannot do the background checks and without doing that they can't establish if the documentation are genuine(standard background checks are a cake walk for the VO and CIO are nowhere near there). Were they able to do that, we would have received medicals from CIO

directly. But they can DECIDE if an application will not pass through if it fails in the MI/6 selection factors/67 points, which they can easily establish with all the supporting documents we have provided. Whereas they cannot be 100% sure if an application that looks OK, is actually OK(unless the BC is done). So, they pass on the file to the VOs to do the Background checks.
Hope that makes sense

Thanks,
Indira Prabhakaran.