I don't know where the "SIPS II" term came from but I will tell you that your system employs the second version of sips bags. The sips bags in outboard seatback bolsters in 95-98 models are impact deployed via a pyrotechnic detonator on end of SIPS frame in seat. 99 onward use an electronic G force sensor signalling the airbag control unit to fire the sips bag. The 99/2000 S/V70 sips bag has an extension that is effectively a pillow to shield the occupant's head from side impact. The 2000 40 series has this also.
The new generation Volvos (S80, 2001 V70, S60) and the 2001 40 series use Inflatable Curtains for head protection and have the torso only sips bags in seats.
Side Impact Protection System is the term Volvo came up with to describe the system that was fitted starting in 92 on 850's (sold as 92 models in Europe) and the 700/900 models. SIPS was actually there in some form even eariler but no name had been granted to it. SIPS is a system of fortifications to the B pillar, roof rails and roof, and rocker panels to make side body more rigid to spread load from impacting vehicle. SIPS also uses a set of transverse pipes as bottom seat frame to take load from door and transfer it across through a fortified box section in center console and to the pipes in other seat and on to the opposite door. The idea being that the interior width should be preserved, even at the expense of pushing body outward on opposite side doing more damge to car body on that side, for lessening or prevention of injuries. Fortifications of parcel shelf in sedans and rear seatbacks in wagons do the same for rear occupants.