public Ptg get3DReferencePtg(AreaReference areaRef, SheetIdentifier sheet) {int extIx = getSheetExtIx(sheet);return new Area3DPtg(areaRef, extIx);}
public Ptg Get3DReferencePtg(CellReference cr, SheetIdentifier sheet){int extIx = GetSheetExtIx(sheet);return new Ref3DPtg(cr, extIx);}