Volvo corporate is holding back in its public online parts system, but why, if it leads to ordering wrong parts?
Because their parts lists are confusing and probably leads to a lot of errors in ordering. Even by the "experts."
My local dealer parts location is a dealer conglomerate of Volvo/BMW/Buick/GMC, and the parts personnel aren't uniquely knowledgeable of Volvo parts. I had an indy replace my axle seals, and Volvo parts rep ordered and sent them the wrong part. Twice. My car sat at the indy for over a week dealing with that issue.
That's probably why my local dealer refuses to run their parts page online. The site was taken down a few years ago and make you call or email to request a part. Given the issues my indy has had, I barely trust them to correct me if I get the wrong parts code from the parts lists on Volvo's site.
I've used them a few times when I'm 99% sure the part I have is what I need but have also resorted to going across the state line to a nearby dealer to buy from their parts department, even to the point of paying taxes on the part vs. no tax in my home state, because they generally do a better job of making sure I'm buying the right part the first time.