replaced brakes on many varieties of cars, except for a Volvo

I have worked on many cars over the years and replaced brakes on many varieties of cars, except for a Volvo. Normally there are 2 main bolts , which when loosened, allow the caliper to be moved and the pads to be taken out. When I loosened the 2 obvious bolts to access the pads, nothing became loose (I removed the retaining clip). I did notice 2 other bolts on the backside of the caliper and wanted to know if these also must be loosened to access the disc pads ( I didn't want to just unknowingly loosen them for fear of actually partially disassembling the caliper itself).

Also, if there is anything else I should know prior to replacing the pads, I would appreciate your input. Your help would be greatly appreciated. Best regards, Robert Herrington