OEM part means original equipment part like what the car came with from the factory, what you'll get if you buy a new part from your Volvo dealer.
The newest type rear pads are not "cutaway", they have a rubber type backing which is attached to the backside of each pad, not removeable.

Although I've seen the half-shims on a few cars (and seen the old SB on this), our dealer has never sold or installed them nor have we seen any problems w/o their use. The older OEM Volvo pads originally came with 2 shims per pad and one would install them with silicone paste on each shim w/o problems at our dealership. Volvo sells and recommends a silicone brake paste that's applied to the backside of new pads which has been around since the 80's (700s) and we use it with every brake job. Our brake jobs do not return to us with any noise or vibration problems nor have they ever.
Rear calipers, pads and rotors on 850s, X70s are almost identicle to what was used in the 80s on 700s and although they have different PNs, 700 and 850 rear pads can even be interchanged (although I'm not advising this here).