Just ask the Subject Access Request (SAR) team what those numbers and what "A2" means. I haven't made SARs with Oxford specifically but surely the SAR team should give you a sheet or something explaining all of the acronyms that they use.
Why I ask is because after receiving back my Subject Access Request, it is mentioned that my overall application grade was an "A2", which I have no clue what it means
My referees were ranked as 5/10/10. Again, no clue what it means either.