rack pannier

My Koga E-lement has a battery pack version of this rear rack. There are four holes (green) and four slots (yellow) running front to back in two of the cross-members. Does anyone know what they're for? Are they fastener locations for paniers? Thanks.

I made use of the 10% off eBay code on Friday and ordered https://www.ebay.co.uk/itm/36V-13Ah-E-bike-Pedelec-Rear-Li-ion-Battery-Carrier-Bracket-w-Lock-Charger/113217309391?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 However, the rack is for V-brake bikes and I've browsed eBay...