Rear Suspension component mounting prescribed area is corroded

Hi

I am looking at an 02 for sale, looks good from pics, got detailed pics of wheel arches, they look fine. I did an MOT history check and last MOT had advisory notices for both nearside and offside: Rear Suspension component mounting prescribed area is corroded but not considered excessive (2.4.A.3)

Anyone know where that is and what it could suggest in terms of wider rust problems?

Many thanks

Andrew