137   SlotIndex Start, Stop;  in update()  local
138   std::tie(Start, Stop) = Indexes->getMBBRange(MBBNum);  in update()
141   if (PrevPos != Start) {  in update()
142     if (!PrevPos.isValid() || Start < PrevPos) {  in update()
145         RUI.VirtI.find(Start);  in update()
146         RUI.FixedI = RUI.Fixed->find(Start);  in update()
151         RUI.VirtI.advanceTo(Start);  in update()
153           RUI.FixedI = RUI.Fixed->advanceTo(RUI.FixedI, Start);  in update()
156     PrevPos = Start;  in update()
216     std::tie(Start, Stop) = Indexes->getMBBRange(MBBNum);  in update()
253   SlotIndex Limit = BI->Last.isValid() ? BI->Last : Start;  in update()