Improve compatibility, fix workbook's rels ID calc error

17 files changed, 213 insertions, 172 deletions

diff --git a/adjust.go b/adjust.go
index bb583f1..c15d4b4 100644
--- a/adjust.go
+++ b/adjust.go
@@ -53,7 +53,7 @@ func (f *File) adjustHelper(sheet string, dir adjustDirection, num, offset int)
 		return err
 	}
 	checkSheet(xlsx)
-	checkRow(xlsx)
+	_ = checkRow(xlsx)
 
 	if xlsx.MergeCells != nil && len(xlsx.MergeCells.Cells) == 0 {
 		xlsx.MergeCells = nil
diff --git a/cell.go b/cell.go
index ad4bcdb..e59a659 100644
--- a/cell.go
+++ b/cell.go
@@ -395,7 +395,7 @@ func (f *File) SetCellHyperLink(sheet, axis, link, linkType string) error {
 		linkData = xlsxHyperlink{
 			Ref: axis,
 		}
-		sheetPath, _ := f.sheetMap[trimSheetName(sheet)]
+		sheetPath := f.sheetMap[trimSheetName(sheet)]
 		sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(sheetPath, "xl/worksheets/") + ".rels"
 		rID := f.addRels(sheetRels, SourceRelationshipHyperLink, link, linkType)
 		linkData.RID = "rId" + strconv.Itoa(rID)
diff --git a/cellmerged.go b/cellmerged.go
index 968a28a..5bea0bc 100644
--- a/cellmerged.go
+++ b/cellmerged.go
@@ -129,8 +129,6 @@ func (f *File) UnmergeCell(sheet string, hcell, vcell string) error {
 	if rect1[3] < rect1[1] {
 		rect1[1], rect1[3] = rect1[3], rect1[1]
 	}
-	hcell, _ = CoordinatesToCellName(rect1[0], rect1[1])
-	vcell, _ = CoordinatesToCellName(rect1[2], rect1[3])
 
 	// return nil since no MergeCells in the sheet
 	if xlsx.MergeCells == nil {
diff --git a/chart.go b/chart.go
index bf8155a..5a42c5b 100644
--- a/chart.go
+++ b/chart.go
@@ -726,8 +726,7 @@ func (f *File) prepareDrawing(xlsx *xlsxWorksheet, drawingID int, sheet, drawing
 		drawingXML = strings.Replace(sheetRelationshipsDrawingXML, "..", "xl", -1)
 	} else {
 		// Add first picture for given sheet.
-		sheetPath, _ := f.sheetMap[trimSheetName(sheet)]
-		sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(sheetPath, "xl/worksheets/") + ".rels"
+		sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(f.sheetMap[trimSheetName(sheet)], "xl/worksheets/") + ".rels"
 		rID := f.addRels(sheetRels, SourceRelationshipDrawingML, sheetRelationshipsDrawingXML, "")
 		f.addSheetDrawing(sheet, rID)
 	}
@@ -743,9 +742,9 @@ func (f *File) addChart(formatSet *formatChart) {
 		XMLNSa:         NameSpaceDrawingML,
 		XMLNSr:         SourceRelationship,
 		XMLNSc16r2:     SourceRelationshipChart201506,
-		Date1904:       &attrValBool{Val: false},
-		Lang:           &attrValString{Val: "en-US"},
-		RoundedCorners: &attrValBool{Val: false},
+		Date1904:       &attrValBool{Val: boolPtr(false)},
+		Lang:           &attrValString{Val: stringPtr("en-US")},
+		RoundedCorners: &attrValBool{Val: boolPtr(false)},
 		Chart: cChart{
 			Title: &cTitle{
 				Tx: cTx{
@@ -761,10 +760,10 @@ func (f *File) addChart(formatSet *formatChart) {
 										SchemeClr: &aSchemeClr{
 											Val: "tx1",
 											LumMod: &attrValInt{
-												Val: 65000,
+												Val: intPtr(65000),
 											},
 											LumOff: &attrValInt{
-												Val: 35000,
+												Val: intPtr(35000),
 											},
 										},
 									},
@@ -806,29 +805,29 @@ func (f *File) addChart(formatSet *formatChart) {
 				},
 			},
 			View3D: &cView3D{
-				RotX:        &attrValInt{Val: chartView3DRotX[formatSet.Type]},
-				RotY:        &attrValInt{Val: chartView3DRotY[formatSet.Type]},
-				Perspective: &attrValInt{Val: chartView3DPerspective[formatSet.Type]},
-				RAngAx:      &attrValInt{Val: chartView3DRAngAx[formatSet.Type]},
+				RotX:        &attrValInt{Val: intPtr(chartView3DRotX[formatSet.Type])},
+				RotY:        &attrValInt{Val: intPtr(chartView3DRotY[formatSet.Type])},
+				Perspective: &attrValInt{Val: intPtr(chartView3DPerspective[formatSet.Type])},
+				RAngAx:      &attrValInt{Val: intPtr(chartView3DRAngAx[formatSet.Type])},
 			},
 			Floor: &cThicknessSpPr{
-				Thickness: &attrValInt{Val: 0},
+				Thickness: &attrValInt{Val: intPtr(0)},
 			},
 			SideWall: &cThicknessSpPr{
-				Thickness: &attrValInt{Val: 0},
+				Thickness: &attrValInt{Val: intPtr(0)},
 			},
 			BackWall: &cThicknessSpPr{
-				Thickness: &attrValInt{Val: 0},
+				Thickness: &attrValInt{Val: intPtr(0)},
 			},
 			PlotArea: &cPlotArea{},
 			Legend: &cLegend{
-				LegendPos: &attrValString{Val: chartLegendPosition[formatSet.Legend.Position]},
-				Overlay:   &attrValBool{Val: false},
+				LegendPos: &attrValString{Val: stringPtr(chartLegendPosition[formatSet.Legend.Position])},
+				Overlay:   &attrValBool{Val: boolPtr(false)},
 			},
 
-			PlotVisOnly:      &attrValBool{Val: false},
-			DispBlanksAs:     &attrValString{Val: formatSet.ShowBlanksAs},
-			ShowDLblsOverMax: &attrValBool{Val: false},
+			PlotVisOnly:      &attrValBool{Val: boolPtr(false)},
+			DispBlanksAs:     &attrValString{Val: stringPtr(formatSet.ShowBlanksAs)},
+			ShowDLblsOverMax: &attrValBool{Val: boolPtr(false)},
 		},
 		SpPr: &cSpPr{
 			SolidFill: &aSolidFill{
@@ -842,10 +841,10 @@ func (f *File) addChart(formatSet *formatChart) {
 				SolidFill: &aSolidFill{
 					SchemeClr: &aSchemeClr{Val: "tx1",
 						LumMod: &attrValInt{
-							Val: 15000,
+							Val: intPtr(15000),
 						},
 						LumOff: &attrValInt{
-							Val: 85000,
+							Val: intPtr(85000),
 						},
 					},
 				},
@@ -928,31 +927,31 @@ func (f *File) addChart(formatSet *formatChart) {
 func (f *File) drawBaseChart(formatSet *formatChart) *cPlotArea {
 	c := cCharts{
 		BarDir: &attrValString{
-			Val: "col",
+			Val: stringPtr("col"),
 		},
 		Grouping: &attrValString{
-			Val: "clustered",
+			Val: stringPtr("clustered"),
 		},
 		VaryColors: &attrValBool{
-			Val: true,
+			Val: boolPtr(true),
 		},
 		Ser:   f.drawChartSeries(formatSet),
 		Shape: f.drawChartShape(formatSet),
 		DLbls: f.drawChartDLbls(formatSet),
 		AxID: []*attrValInt{
-			{Val: 754001152},
-			{Val: 753999904},
+			{Val: intPtr(754001152)},
+			{Val: intPtr(753999904)},
 		},
-		Overlap: &attrValInt{Val: 100},
+		Overlap: &attrValInt{Val: intPtr(100)},
 	}
 	var ok bool
-	if c.BarDir.Val, ok = plotAreaChartBarDir[formatSet.Type]; !ok {
+	if *c.BarDir.Val, ok = plotAreaChartBarDir[formatSet.Type]; !ok {
 		c.BarDir = nil
 	}
-	if c.Grouping.Val, ok = plotAreaChartGrouping[formatSet.Type]; !ok {
+	if *c.Grouping.Val, ok = plotAreaChartGrouping[formatSet.Type]; !ok {
 		c.Grouping = nil
 	}
-	if c.Overlap.Val, ok = plotAreaChartOverlap[formatSet.Type]; !ok {
+	if *c.Overlap.Val, ok = plotAreaChartOverlap[formatSet.Type]; !ok {
 		c.Overlap = nil
 	}
 	catAx := f.drawPlotAreaCatAx(formatSet)
@@ -1178,10 +1177,10 @@ func (f *File) drawDoughnutChart(formatSet *formatChart) *cPlotArea {
 	return &cPlotArea{
 		DoughnutChart: &cCharts{
 			VaryColors: &attrValBool{
-				Val: true,
+				Val: boolPtr(true),
 			},
 			Ser:      f.drawChartSeries(formatSet),
-			HoleSize: &attrValInt{Val: 75},
+			HoleSize: &attrValInt{Val: intPtr(75)},
 		},
 	}
 }
@@ -1192,19 +1191,19 @@ func (f *File) drawLineChart(formatSet *formatChart) *cPlotArea {
 	return &cPlotArea{
 		LineChart: &cCharts{
 			Grouping: &attrValString{
-				Val: plotAreaChartGrouping[formatSet.Type],
+				Val: stringPtr(plotAreaChartGrouping[formatSet.Type]),
 			},
 			VaryColors: &attrValBool{
-				Val: false,
+				Val: boolPtr(false),
 			},
 			Ser:   f.drawChartSeries(formatSet),
 			DLbls: f.drawChartDLbls(formatSet),
 			Smooth: &attrValBool{
-				Val: false,
+				Val: boolPtr(false),
 			},
 			AxID: []*attrValInt{
-				{Val: 754001152},
-				{Val: 753999904},
+				{Val: intPtr(754001152)},
+				{Val: intPtr(753999904)},
 			},
 		},
 		CatAx: f.drawPlotAreaCatAx(formatSet),
@@ -1218,7 +1217,7 @@ func (f *File) drawPieChart(formatSet *formatChart) *cPlotArea {
 	return &cPlotArea{
 		PieChart: &cCharts{
 			VaryColors: &attrValBool{
-				Val: true,
+				Val: boolPtr(true),
 			},
 			Ser: f.drawChartSeries(formatSet),
 		},
@@ -1231,7 +1230,7 @@ func (f *File) drawPie3DChart(formatSet *formatChart) *cPlotArea {
 	return &cPlotArea{
 		Pie3DChart: &cCharts{
 			VaryColors: &attrValBool{
-				Val: true,
+				Val: boolPtr(true),
 			},
 			Ser: f.drawChartSeries(formatSet),
 		},
@@ -1244,16 +1243,16 @@ func (f *File) drawRadarChart(formatSet *formatChart) *cPlotArea {
 	return &cPlotArea{
 		RadarChart: &cCharts{
 			RadarStyle: &attrValString{
-				Val: "marker",
+				Val: stringPtr("marker"),
 			},
 			VaryColors: &attrValBool{
-				Val: false,
+				Val: boolPtr(false),
 			},
 			Ser:   f.drawChartSeries(formatSet),
 			DLbls: f.drawChartDLbls(formatSet),
 			AxID: []*attrValInt{
-				{Val: 754001152},
-				{Val: 753999904},
+				{Val: intPtr(754001152)},
+				{Val: intPtr(753999904)},
 			},
 		},
 		CatAx: f.drawPlotAreaCatAx(formatSet),
@@ -1267,16 +1266,16 @@ func (f *File) drawScatterChart(formatSet *formatChart) *cPlotArea {
 	return &cPlotArea{
 		ScatterChart: &cCharts{
 			ScatterStyle: &attrValString{
-				Val: "smoothMarker", // line,lineMarker,marker,none,smooth,smoothMarker
+				Val: stringPtr("smoothMarker"), // line,lineMarker,marker,none,smooth,smoothMarker
 			},
 			VaryColors: &attrValBool{
-				Val: false,
+				Val: boolPtr(false),
 			},
 			Ser:   f.drawChartSeries(formatSet),
 			DLbls: f.drawChartDLbls(formatSet),
 			AxID: []*attrValInt{
-				{Val: 754001152},
-				{Val: 753999904},
+				{Val: intPtr(754001152)},
+				{Val: intPtr(753999904)},
 			},
 		},
 		CatAx: f.drawPlotAreaCatAx(formatSet),
@@ -1291,9 +1290,9 @@ func (f *File) drawSurface3DChart(formatSet *formatChart) *cPlotArea {
 		Surface3DChart: &cCharts{
 			Ser: f.drawChartSeries(formatSet),
 			AxID: []*attrValInt{
-				{Val: 754001152},
-				{Val: 753999904},
-				{Val: 832256642},
+				{Val: intPtr(754001152)},
+				{Val: intPtr(753999904)},
+				{Val: intPtr(832256642)},
 			},
 		},
 		CatAx: f.drawPlotAreaCatAx(formatSet),
@@ -1301,7 +1300,7 @@ func (f *File) drawSurface3DChart(formatSet *formatChart) *cPlotArea {
 		SerAx: f.drawPlotAreaSerAx(formatSet),
 	}
 	if formatSet.Type == WireframeSurface3D {
-		plotArea.Surface3DChart.Wireframe = &attrValBool{Val: true}
+		plotArea.Surface3DChart.Wireframe = &attrValBool{Val: boolPtr(true)}
 	}
 	return plotArea
 }
@@ -1313,9 +1312,9 @@ func (f *File) drawSurfaceChart(formatSet *formatChart) *cPlotArea {
 		SurfaceChart: &cCharts{
 			Ser: f.drawChartSeries(formatSet),
 			AxID: []*attrValInt{
-				{Val: 754001152},
-				{Val: 753999904},
-				{Val: 832256642},
+				{Val: intPtr(754001152)},
+				{Val: intPtr(753999904)},
+				{Val: intPtr(832256642)},
 			},
 		},
 		CatAx: f.drawPlotAreaCatAx(formatSet),
@@ -1323,7 +1322,7 @@ func (f *File) drawSurfaceChart(formatSet *formatChart) *cPlotArea {
 		SerAx: f.drawPlotAreaSerAx(formatSet),
 	}
 	if formatSet.Type == WireframeContour {
-		plotArea.SurfaceChart.Wireframe = &attrValBool{Val: true}
+		plotArea.SurfaceChart.Wireframe = &attrValBool{Val: boolPtr(true)}
 	}
 	return plotArea
 }
@@ -1355,7 +1354,7 @@ func (f *File) drawChartShape(formatSet *formatChart) *attrValString {
 		Col3DCylinderPercentStacked: "cylinder",
 	}
 	if shape, ok := shapes[formatSet.Type]; ok {
-		return &attrValString{Val: shape}
+		return &attrValString{Val: stringPtr(shape)}
 	}
 	return nil
 }
@@ -1366,8 +1365,8 @@ func (f *File) drawChartSeries(formatSet *formatChart) *[]cSer {
 	ser := []cSer{}
 	for k := range formatSet.Series {
 		ser = append(ser, cSer{
-			IDx:   &attrValInt{Val: k},
-			Order: &attrValInt{Val: k},
+			IDx:   &attrValInt{Val: intPtr(k)},
+			Order: &attrValInt{Val: intPtr(k)},
 			Tx: &cTx{
 				StrRef: &cStrRef{
 					F: formatSet.Series[k].Name,
@@ -1416,8 +1415,8 @@ func (f *File) drawChartSeriesSpPr(i int, formatSet *formatChart) *cSpPr {
 // data index and format sets.
 func (f *File) drawChartSeriesDPt(i int, formatSet *formatChart) []*cDPt {
 	dpt := []*cDPt{{
-		IDx:      &attrValInt{Val: i},
-		Bubble3D: &attrValBool{Val: false},
+		IDx:      &attrValInt{Val: intPtr(i)},
+		Bubble3D: &attrValBool{Val: boolPtr(false)},
 		SpPr: &cSpPr{
 			SolidFill: &aSolidFill{
 				SchemeClr: &aSchemeClr{Val: "accent" + strconv.Itoa(i+1)},
@@ -1475,8 +1474,8 @@ func (f *File) drawChartSeriesVal(v formatChartSeries, formatSet *formatChart) *
 // given data index and format sets.
 func (f *File) drawChartSeriesMarker(i int, formatSet *formatChart) *cMarker {
 	marker := &cMarker{
-		Symbol: &attrValString{Val: "circle"},
-		Size:   &attrValInt{Val: 5},
+		Symbol: &attrValString{Val: stringPtr("circle")},
+		Size:   &attrValInt{Val: intPtr(5)},
 	}
 	if i < 6 {
 		marker.SpPr = &cSpPr{
@@ -1542,20 +1541,20 @@ func (f *File) drawCharSeriesBubble3D(formatSet *formatChart) *attrValBool {
 	if _, ok := map[string]bool{Bubble3D: true}[formatSet.Type]; !ok {
 		return nil
 	}
-	return &attrValBool{Val: true}
+	return &attrValBool{Val: boolPtr(true)}
 }
 
 // drawChartDLbls provides a function to draw the c:dLbls element by given
 // format sets.
 func (f *File) drawChartDLbls(formatSet *formatChart) *cDLbls {
 	return &cDLbls{
-		ShowLegendKey:   &attrValBool{Val: formatSet.Legend.ShowLegendKey},
-		ShowVal:         &attrValBool{Val: formatSet.Plotarea.ShowVal},
-		ShowCatName:     &attrValBool{Val: formatSet.Plotarea.ShowCatName},
-		ShowSerName:     &attrValBool{Val: formatSet.Plotarea.ShowSerName},
-		ShowBubbleSize:  &attrValBool{Val: formatSet.Plotarea.ShowBubbleSize},
-		ShowPercent:     &attrValBool{Val: formatSet.Plotarea.ShowPercent},
-		ShowLeaderLines: &attrValBool{Val: formatSet.Plotarea.ShowLeaderLines},
+		ShowLegendKey:   &attrValBool{Val: boolPtr(formatSet.Legend.ShowLegendKey)},
+		ShowVal:         &attrValBool{Val: boolPtr(formatSet.Plotarea.ShowVal)},
+		ShowCatName:     &attrValBool{Val: boolPtr(formatSet.Plotarea.ShowCatName)},
+		ShowSerName:     &attrValBool{Val: boolPtr(formatSet.Plotarea.ShowSerName)},
+		ShowBubbleSize:  &attrValBool{Val: boolPtr(formatSet.Plotarea.ShowBubbleSize)},
+		ShowPercent:     &attrValBool{Val: boolPtr(formatSet.Plotarea.ShowPercent)},
+		ShowLeaderLines: &attrValBool{Val: boolPtr(formatSet.Plotarea.ShowLeaderLines)},
 	}
 }
 
@@ -1572,8 +1571,8 @@ func (f *File) drawChartSeriesDLbls(formatSet *formatChart) *cDLbls {
 
 // drawPlotAreaCatAx provides a function to draw the c:catAx element.
 func (f *File) drawPlotAreaCatAx(formatSet *formatChart) []*cAxs {
-	min := &attrValFloat{Val: formatSet.XAxis.Minimum}
-	max := &attrValFloat{Val: formatSet.XAxis.Maximum}
+	min := &attrValFloat{Val: float64Ptr(formatSet.XAxis.Minimum)}
+	max := &attrValFloat{Val: float64Ptr(formatSet.XAxis.Maximum)}
 	if formatSet.XAxis.Minimum == 0 {
 		min = nil
 	}
@@ -1582,29 +1581,29 @@ func (f *File) drawPlotAreaCatAx(formatSet *formatChart) []*cAxs {
 	}
 	axs := []*cAxs{
 		{
-			AxID: &attrValInt{Val: 754001152},
+			AxID: &attrValInt{Val: intPtr(754001152)},
 			Scaling: &cScaling{
-				Orientation: &attrValString{Val: orientation[formatSet.XAxis.ReverseOrder]},
+				Orientation: &attrValString{Val: stringPtr(orientation[formatSet.XAxis.ReverseOrder])},
 				Max:         max,
 				Min:         min,
 			},
-			Delete: &attrValBool{Val: false},
-			AxPos:  &attrValString{Val: catAxPos[formatSet.XAxis.ReverseOrder]},
+			Delete: &attrValBool{Val: boolPtr(false)},
+			AxPos:  &attrValString{Val: stringPtr(catAxPos[formatSet.XAxis.ReverseOrder])},
 			NumFmt: &cNumFmt{
 				FormatCode:   "General",
 				SourceLinked: true,
 			},
-			MajorTickMark: &attrValString{Val: "none"},
-			MinorTickMark: &attrValString{Val: "none"},
-			TickLblPos:    &attrValString{Val: "nextTo"},
+			MajorTickMark: &attrValString{Val: stringPtr("none")},
+			MinorTickMark: &attrValString{Val: stringPtr("none")},
+			TickLblPos:    &attrValString{Val: stringPtr("nextTo")},
 			SpPr:          f.drawPlotAreaSpPr(),
 			TxPr:          f.drawPlotAreaTxPr(),
-			CrossAx:       &attrValInt{Val: 753999904},
-			Crosses:       &attrValString{Val: "autoZero"},
-			Auto:          &attrValBool{Val: true},
-			LblAlgn:       &attrValString{Val: "ctr"},
-			LblOffset:     &attrValInt{Val: 100},
-			NoMultiLvlLbl: &attrValBool{Val: false},
+			CrossAx:       &attrValInt{Val: intPtr(753999904)},
+			Crosses:       &attrValString{Val: stringPtr("autoZero")},
+			Auto:          &attrValBool{Val: boolPtr(true)},
+			LblAlgn:       &attrValString{Val: stringPtr("ctr")},
+			LblOffset:     &attrValInt{Val: intPtr(100)},
+			NoMultiLvlLbl: &attrValBool{Val: boolPtr(false)},
 		},
 	}
 	if formatSet.XAxis.MajorGridlines {
@@ -1618,8 +1617,8 @@ func (f *File) drawPlotAreaCatAx(formatSet *formatChart) []*cAxs {
 
 // drawPlotAreaValAx provides a function to draw the c:valAx element.
 func (f *File) drawPlotAreaValAx(formatSet *formatChart) []*cAxs {
-	min := &attrValFloat{Val: formatSet.YAxis.Minimum}
-	max := &attrValFloat{Val: formatSet.YAxis.Maximum}
+	min := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Minimum)}
+	max := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Maximum)}
 	if formatSet.YAxis.Minimum == 0 {
 		min = nil
 	}
@@ -1628,26 +1627,26 @@ func (f *File) drawPlotAreaValAx(formatSet *formatChart) []*cAxs {
 	}
 	axs := []*cAxs{
 		{
-			AxID: &attrValInt{Val: 753999904},
+			AxID: &attrValInt{Val: intPtr(753999904)},
 			Scaling: &cScaling{
-				Orientation: &attrValString{Val: orientation[formatSet.YAxis.ReverseOrder]},
+				Orientation: &attrValString{Val: stringPtr(orientation[formatSet.YAxis.ReverseOrder])},
 				Max:         max,
 				Min:         min,
 			},
-			Delete: &attrValBool{Val: false},
-			AxPos:  &attrValString{Val: valAxPos[formatSet.YAxis.ReverseOrder]},
+			Delete: &attrValBool{Val: boolPtr(false)},
+			AxPos:  &attrValString{Val: stringPtr(valAxPos[formatSet.YAxis.ReverseOrder])},
 			NumFmt: &cNumFmt{
 				FormatCode:   chartValAxNumFmtFormatCode[formatSet.Type],
 				SourceLinked: true,
 			},
-			MajorTickMark: &attrValString{Val: "none"},
-			MinorTickMark: &attrValString{Val: "none"},
-			TickLblPos:    &attrValString{Val: "nextTo"},
+			MajorTickMark: &attrValString{Val: stringPtr("none")},
+			MinorTickMark: &attrValString{Val: stringPtr("none")},
+			TickLblPos:    &attrValString{Val: stringPtr("nextTo")},
 			SpPr:          f.drawPlotAreaSpPr(),
 			TxPr:          f.drawPlotAreaTxPr(),
-			CrossAx:       &attrValInt{Val: 754001152},
-			Crosses:       &attrValString{Val: "autoZero"},
-			CrossBetween:  &attrValString{Val: chartValAxCrossBetween[formatSet.Type]},
+			CrossAx:       &attrValInt{Val: intPtr(754001152)},
+			Crosses:       &attrValString{Val: stringPtr("autoZero")},
+			CrossBetween:  &attrValString{Val: stringPtr(chartValAxCrossBetween[formatSet.Type])},
 		},
 	}
 	if formatSet.YAxis.MajorGridlines {
@@ -1657,15 +1656,15 @@ func (f *File) drawPlotAreaValAx(formatSet *formatChart) []*cAxs {
 		axs[0].MinorGridlines = &cChartLines{SpPr: f.drawPlotAreaSpPr()}
 	}
 	if pos, ok := valTickLblPos[formatSet.Type]; ok {
-		axs[0].TickLblPos.Val = pos
+		axs[0].TickLblPos.Val = stringPtr(pos)
 	}
 	return axs
 }
 
 // drawPlotAreaSerAx provides a function to draw the c:serAx element.
 func (f *File) drawPlotAreaSerAx(formatSet *formatChart) []*cAxs {
-	min := &attrValFloat{Val: formatSet.YAxis.Minimum}
-	max := &attrValFloat{Val: formatSet.YAxis.Maximum}
+	min := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Minimum)}
+	max := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Maximum)}
 	if formatSet.YAxis.Minimum == 0 {
 		min = nil
 	}
@@ -1674,18 +1673,18 @@ func (f *File) drawPlotAreaSerAx(formatSet *formatChart) []*cAxs {
 	}
 	return []*cAxs{
 		{
-			AxID: &attrValInt{Val: 832256642},
+			AxID: &attrValInt{Val: intPtr(832256642)},
 			Scaling: &cScaling{
-				Orientation: &attrValString{Val: orientation[formatSet.YAxis.ReverseOrder]},
+				Orientation: &attrValString{Val: stringPtr(orientation[formatSet.YAxis.ReverseOrder])},
 				Max:         max,
 				Min:         min,
 			},
-			Delete:     &attrValBool{Val: false},
-			AxPos:      &attrValString{Val: catAxPos[formatSet.XAxis.ReverseOrder]},
-			TickLblPos: &attrValString{Val: "nextTo"},
+			Delete:     &attrValBool{Val: boolPtr(false)},
+			AxPos:      &attrValString{Val: stringPtr(catAxPos[formatSet.XAxis.ReverseOrder])},
+			TickLblPos: &attrValString{Val: stringPtr("nextTo")},
 			SpPr:       f.drawPlotAreaSpPr(),
 			TxPr:       f.drawPlotAreaTxPr(),
-			CrossAx:    &attrValInt{Val: 753999904},
+			CrossAx:    &attrValInt{Val: intPtr(753999904)},
 		},
 	}
 }
@@ -1701,8 +1700,8 @@ func (f *File) drawPlotAreaSpPr() *cSpPr {
 			SolidFill: &aSolidFill{
 				SchemeClr: &aSchemeClr{
 					Val:    "tx1",
-					LumMod: &attrValInt{Val: 15000},
-					LumOff: &attrValInt{Val: 85000},
+					LumMod: &attrValInt{Val: intPtr(15000)},
+					LumOff: &attrValInt{Val: intPtr(85000)},
 				},
 			},
 		},
@@ -1734,8 +1733,8 @@ func (f *File) drawPlotAreaTxPr() *cTxPr {
 					SolidFill: &aSolidFill{
 						SchemeClr: &aSchemeClr{
 							Val:    "tx1",
-							LumMod: &attrValInt{Val: 15000},
-							LumOff: &attrValInt{Val: 85000},
+							LumMod: &attrValInt{Val: intPtr(15000)},
+							LumOff: &attrValInt{Val: intPtr(85000)},
 						},
 					},
 					Latin: &aLatin{Typeface: "+mn-lt"},
diff --git a/comment.go b/comment.go
index 99630c9..486a035 100644
--- a/comment.go
+++ b/comment.go
@@ -101,8 +101,7 @@ func (f *File) AddComment(sheet, cell, format string) error {
 		drawingVML = strings.Replace(sheetRelationshipsDrawingVML, "..", "xl", -1)
 	} else {
 		// Add first comment for given sheet.
-		sheetPath, _ := f.sheetMap[trimSheetName(sheet)]
-		sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(sheetPath, "xl/worksheets/") + ".rels"
+		sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(f.sheetMap[trimSheetName(sheet)], "xl/worksheets/") + ".rels"
 		rID := f.addRels(sheetRels, SourceRelationshipDrawingVML, sheetRelationshipsDrawingVML, "")
 		f.addRels(sheetRels, SourceRelationshipComments, sheetRelationshipsComments, "")
 		f.addSheetLegacyDrawing(sheet, rID)
@@ -256,23 +255,23 @@ func (f *File) addComment(commentsXML, cell string, formatSet *formatComment) {
 				{
 					RPr: &xlsxRPr{
 						B:  " ",
-						Sz: &attrValFloat{Val: 9},
+						Sz: &attrValFloat{Val: float64Ptr(9)},
 						Color: &xlsxColor{
 							Indexed: 81,
 						},
-						RFont:  &attrValString{Val: defaultFont},
-						Family: &attrValInt{Val: 2},
+						RFont:  &attrValString{Val: stringPtr(defaultFont)},
+						Family: &attrValInt{Val: intPtr(2)},
 					},
 					T: a,
 				},
 				{
 					RPr: &xlsxRPr{
-						Sz: &attrValFloat{Val: 9},
+						Sz: &attrValFloat{Val: float64Ptr(9)},
 						Color: &xlsxColor{
 							Indexed: 81,
 						},
-						RFont:  &attrValString{Val: defaultFont},
-						Family: &attrValInt{Val: 2},
+						RFont:  &attrValString{Val: stringPtr(defaultFont)},
+						Family: &attrValInt{Val: intPtr(2)},
 					},
 					T: t,
 				},
diff --git a/excelize.go b/excelize.go
index a2e20ff..135028c 100644
--- a/excelize.go
+++ b/excelize.go
@@ -203,11 +203,17 @@ func checkSheet(xlsx *xlsxWorksheet) {
 // relationship type, target and target mode.
 func (f *File) addRels(relPath, relType, target, targetMode string) int {
 	rels := f.relsReader(relPath)
-	rID := 0
 	if rels == nil {
 		rels = &xlsxRelationships{}
 	}
-	rID = len(rels.Relationships) + 1
+	var rID int
+	for _, rel := range rels.Relationships {
+		ID, _ := strconv.Atoi(strings.TrimPrefix(rel.ID, "rId"))
+		if ID > rID {
+			rID = ID
+		}
+	}
+	rID++
 	var ID bytes.Buffer
 	ID.WriteString("rId")
 	ID.WriteString(strconv.Itoa(rID))
diff --git a/excelize_test.go b/excelize_test.go
index 6929a4f..1d6ed24 100644
--- a/excelize_test.go
+++ b/excelize_test.go
@@ -48,7 +48,7 @@ func TestOpenFile(t *testing.T) {
 	assert.EqualError(t, f.SetCellDefault("Sheet2", "A", strconv.FormatFloat(float64(-100.1588), 'f', -1, 64)),
 		`cannot convert cell "A" to coordinates: invalid cell name "A"`)
 
-	f.SetCellInt("Sheet2", "A1", 100)
+	assert.NoError(t, f.SetCellInt("Sheet2", "A1", 100))
 
 	// Test set cell integer value with illegal row number.
 	assert.EqualError(t, f.SetCellInt("Sheet2", "A", 100), `cannot convert cell "A" to coordinates: invalid cell name "A"`)
@@ -80,8 +80,10 @@ func TestOpenFile(t *testing.T) {
 	_, err = f.GetCellFormula("Sheet1", "B")
 	assert.EqualError(t, err, `cannot convert cell "B" to coordinates: invalid cell name "B"`)
 	// Test get shared cell formula
-	f.GetCellFormula("Sheet2", "H11")
-	f.GetCellFormula("Sheet2", "I11")
+	_, err = f.GetCellFormula("Sheet2", "H11")
+	assert.NoError(t, err)
+	_, err = f.GetCellFormula("Sheet2", "I11")
+	assert.NoError(t, err)
 	getSharedForumula(&xlsxWorksheet{}, "")
 
 	// Test read cell value with given illegal rows number.
@@ -91,10 +93,14 @@ func TestOpenFile(t *testing.T) {
 	assert.EqualError(t, err, `cannot convert cell "A" to coordinates: invalid cell name "A"`)
 
 	// Test read cell value with given lowercase column number.
-	f.GetCellValue("Sheet2", "a5")
-	f.GetCellValue("Sheet2", "C11")
-	f.GetCellValue("Sheet2", "D11")
-	f.GetCellValue("Sheet2", "D12")
+	_, err = f.GetCellValue("Sheet2", "a5")
+	assert.NoError(t, err)
+	_, err = f.GetCellValue("Sheet2", "C11")
+	assert.NoError(t, err)
+	_, err = f.GetCellValue("Sheet2", "D11")
+	assert.NoError(t, err)
+	_, err = f.GetCellValue("Sheet2", "D12")
+	assert.NoError(t, err)
 	// Test SetCellValue function.
 	assert.NoError(t, f.SetCellValue("Sheet2", "F1", " Hello"))
 	assert.NoError(t, f.SetCellValue("Sheet2", "G1", []byte("World")))
@@ -147,7 +153,8 @@ func TestOpenFile(t *testing.T) {
 	// Test completion column.
 	f.SetCellValue("Sheet2", "M2", nil)
 	// Test read cell value with given axis large than exists row.
-	f.GetCellValue("Sheet2", "E231")
+	_, err = f.GetCellValue("Sheet2", "E231")
+	assert.NoError(t, err)
 	// Test get active worksheet of XLSX and get worksheet name of XLSX by given worksheet index.
 	f.GetSheetName(f.GetActiveSheetIndex())
 	// Test get worksheet index of XLSX by given worksheet name.
@@ -302,13 +309,10 @@ func TestSetCellHyperLink(t *testing.T) {
 
 	assert.NoError(t, f.SaveAs(filepath.Join("test", "TestSetCellHyperLink.xlsx")))
 
-	file := NewFile()
-	for row := 1; row <= 65530; row++ {
-		cell, err := CoordinatesToCellName(1, row)
-		assert.NoError(t, err)
-		assert.NoError(t, file.SetCellHyperLink("Sheet1", cell, "https://github.com/360EntSecGroup-Skylar/excelize", "External"))
-	}
-	assert.EqualError(t, file.SetCellHyperLink("Sheet1", "A65531", "https://github.com/360EntSecGroup-Skylar/excelize", "External"), "over maximum limit hyperlinks in a worksheet")
+	f = NewFile()
+	f.workSheetReader("Sheet1")
+	f.Sheet["xl/worksheets/sheet1.xml"].Hyperlinks = &xlsxHyperlinks{Hyperlink: make([]xlsxHyperlink, 65530)}
+	assert.EqualError(t, f.SetCellHyperLink("Sheet1", "A65531", "https://github.com/360EntSecGroup-Skylar/excelize", "External"), "over maximum limit hyperlinks in a worksheet")
 
 	f = NewFile()
 	f.workSheetReader("Sheet1")
@@ -1013,6 +1017,8 @@ func TestSetActiveSheet(t *testing.T) {
 	f.WorkBook.BookViews = &xlsxBookViews{WorkBookView: []xlsxWorkBookView{}}
 	f.Sheet["xl/worksheets/sheet1.xml"].SheetViews = &xlsxSheetViews{SheetView: []xlsxSheetView{}}
 	f.SetActiveSheet(1)
+	f.Sheet["xl/worksheets/sheet1.xml"].SheetViews = nil
+	f.SetActiveSheet(1)
 }
 
 func TestSetSheetVisible(t *testing.T) {
diff --git a/lib.go b/lib.go
index edac98a..86f8d16 100644
--- a/lib.go
+++ b/lib.go
@@ -198,6 +198,15 @@ func CoordinatesToCellName(col, row int) (string, error) {
 // boolPtr returns a pointer to a bool with the given value.
 func boolPtr(b bool) *bool { return &b }
 
+// intPtr returns a pointer to a int with the given value.
+func intPtr(i int) *int { return &i }
+
+// float64Ptr returns a pofloat64er to a float64 with the given value.
+func float64Ptr(f float64) *float64 { return &f }
+
+// stringPtr returns a pointer to a string with the given value.
+func stringPtr(s string) *string { return &s }
+
 // defaultTrue returns true if b is nil, or the pointed value.
 func defaultTrue(b *bool) bool {
 	if b == nil {
diff --git a/shape.go b/shape.go
index f284e43..2ea66ea 100644
--- a/shape.go
+++ b/shape.go
@@ -275,8 +275,7 @@ func (f *File) AddShape(sheet, cell, format string) error {
 		drawingXML = strings.Replace(sheetRelationshipsDrawingXML, "..", "xl", -1)
 	} else {
 		// Add first shape for given sheet.
-		name, _ := f.sheetMap[trimSheetName(sheet)]
-		sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(name, "xl/worksheets/") + ".rels"
+		sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(f.sheetMap[trimSheetName(sheet)], "xl/worksheets/") + ".rels"
 		rID := f.addRels(sheetRels, SourceRelationshipDrawingML, sheetRelationshipsDrawingXML, "")
 		f.addSheetDrawing(sheet, rID)
 	}
@@ -362,7 +361,7 @@ func (f *File) addDrawingShape(sheet, drawingXML, cell string, formatSet *format
 			FontRef: &aFontRef{
 				Idx: "minor",
 				SchemeClr: &attrValString{
-					Val: "tx1",
+					Val: stringPtr("tx1"),
 				},
 			},
 		},
@@ -422,7 +421,7 @@ func (f *File) addDrawingShape(sheet, drawingXML, cell string, formatSet *format
 		if len(srgbClr) == 6 {
 			paragraph.R.RPr.SolidFill = &aSolidFill{
 				SrgbClr: &attrValString{
-					Val: srgbClr,
+					Val: stringPtr(srgbClr),
 				},
 			}
 		}
@@ -454,7 +453,7 @@ func setShapeRef(color string, i int) *aRef {
 	return &aRef{
 		Idx: i,
 		SrgbClr: &attrValString{
-			Val: strings.Replace(strings.ToUpper(color), "#", "", -1),
+			Val: stringPtr(strings.Replace(strings.ToUpper(color), "#", "", -1)),
 		},
 	}
 }
diff --git a/sheet.go b/sheet.go
index 7412fce..954de5b 100644
--- a/sheet.go
+++ b/sheet.go
@@ -249,6 +249,11 @@ func (f *File) SetActiveSheet(index int) {
 	}
 	for idx, name := range f.GetSheetMap() {
 		xlsx, _ := f.workSheetReader(name)
+		if xlsx.SheetViews == nil {
+			xlsx.SheetViews = &xlsxSheetViews{
+				SheetView: []xlsxSheetView{{WorkbookViewID: 0}},
+			}
+		}
 		if len(xlsx.SheetViews.SheetView) > 0 {
 			xlsx.SheetViews.SheetView[0].TabSelected = false
 		}
@@ -305,11 +310,15 @@ func (f *File) SetSheetName(oldName, newName string) {
 // string.
 func (f *File) GetSheetName(index int) string {
 	wb := f.workbookReader()
-	realIdx := index - 1 // sheets are 1 based index, but we're checking against an array
-	if wb == nil || realIdx < 0 || realIdx >= len(wb.Sheets.Sheet) {
+	if wb == nil || index < 1 {
 		return ""
 	}
-	return wb.Sheets.Sheet[realIdx].Name
+	for _, sheet := range wb.Sheets.Sheet {
+		if index == sheet.SheetID {
+			return sheet.Name
+		}
+	}
+	return ""
 }
 
 // GetSheetIndex provides a function to get worksheet index of XLSX by given
@@ -342,8 +351,8 @@ func (f *File) GetSheetMap() map[int]string {
 	wb := f.workbookReader()
 	sheetMap := map[int]string{}
 	if wb != nil {
-		for i, sheet := range wb.Sheets.Sheet {
-			sheetMap[i+1] = sheet.Name
+		for _, sheet := range wb.Sheets.Sheet {
+			sheetMap[sheet.SheetID] = sheet.Name
 		}
 	}
 	return sheetMap
@@ -384,8 +393,7 @@ func (f *File) SetSheetBackground(sheet, picture string) error {
 	}
 	file, _ := ioutil.ReadFile(picture)
 	name := f.addMedia(file, ext)
-	sheetPath, _ := f.sheetMap[trimSheetName(sheet)]
-	sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(sheetPath, "xl/worksheets/") + ".rels"
+	sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(f.sheetMap[trimSheetName(sheet)], "xl/worksheets/") + ".rels"
 	rID := f.addRels(sheetRels, SourceRelationshipImage, strings.Replace(name, "xl", "..", 1), "")
 	f.addSheetPicture(sheet, rID)
 	f.setContentTypePartImageExtensions()
diff --git a/stream_test.go b/stream_test.go
index 8371a4e..4482bd1 100644
--- a/stream_test.go
+++ b/stream_test.go
@@ -42,7 +42,7 @@ func TestStreamWriter(t *testing.T) {
 	assert.NoError(t, file.SaveAs(filepath.Join("test", "TestStreamWriter.xlsx")))
 
 	// Test error exceptions
-	streamWriter, err = file.NewStreamWriter("SheetN")
+	_, err = file.NewStreamWriter("SheetN")
 	assert.EqualError(t, err, "sheet SheetN is not exist")
 }
 
diff --git a/styles.go b/styles.go
index fa0507e..56c7196 100644
--- a/styles.go
+++ b/styles.go
@@ -1957,13 +1957,13 @@ func (f *File) NewConditionalStyle(style string) (int, error) {
 // Documents generated by excelize start with Calibri.
 func (f *File) GetDefaultFont() string {
 	font := f.readDefaultFont()
-	return font.Name.Val
+	return *font.Name.Val
 }
 
 // SetDefaultFont changes the default font in the workbook.
 func (f *File) SetDefaultFont(fontName string) {
 	font := f.readDefaultFont()
-	font.Name.Val = fontName
+	font.Name.Val = stringPtr(fontName)
 	s := f.stylesReader()
 	s.Fonts.Font[0] = font
 	custom := true
@@ -1987,10 +1987,10 @@ func (f *File) setFont(formatStyle *formatStyle) *xlsxFont {
 		formatStyle.Font.Color = "#000000"
 	}
 	fnt := xlsxFont{
-		Sz:     &attrValFloat{Val: formatStyle.Font.Size},
+		Sz:     &attrValFloat{Val: float64Ptr(formatStyle.Font.Size)},
 		Color:  &xlsxColor{RGB: getPaletteColor(formatStyle.Font.Color)},
-		Name:   &attrValString{Val: formatStyle.Font.Family},
-		Family: &attrValInt{Val: 2},
+		Name:   &attrValString{Val: stringPtr(formatStyle.Font.Family)},
+		Family: &attrValInt{Val: intPtr(2)},
 	}
 	if formatStyle.Font.Bold {
 		fnt.B = &formatStyle.Font.Bold
@@ -1998,8 +1998,8 @@ func (f *File) setFont(formatStyle *formatStyle) *xlsxFont {
 	if formatStyle.Font.Italic {
 		fnt.I = &formatStyle.Font.Italic
 	}
-	if fnt.Name.Val == "" {
-		fnt.Name.Val = f.GetDefaultFont()
+	if *fnt.Name.Val == "" {
+		*fnt.Name.Val = f.GetDefaultFont()
 	}
 	if formatStyle.Font.Strike {
 		strike := true
@@ -2007,7 +2007,7 @@ func (f *File) setFont(formatStyle *formatStyle) *xlsxFont {
 	}
 	val, ok := fontUnderlineType[formatStyle.Font.Underline]
 	if ok {
-		fnt.U = &attrValString{Val: val}
+		fnt.U = &attrValString{Val: stringPtr(val)}
 	}
 	return &fnt
 }
diff --git a/styles_test.go b/styles_test.go
index 36a78ed..e6faccb 100644
--- a/styles_test.go
+++ b/styles_test.go
@@ -175,7 +175,7 @@ func TestNewStyle(t *testing.T) {
 	styles := f.stylesReader()
 	fontID := styles.CellXfs.Xf[styleID].FontID
 	font := styles.Fonts.Font[fontID]
-	assert.Contains(t, font.Name.Val, "Times New Roman", "Stored font should contain font name")
+	assert.Contains(t, *font.Name.Val, "Times New Roman", "Stored font should contain font name")
 	assert.Equal(t, 2, styles.CellXfs.Count, "Should have 2 styles")
 }
 
diff --git a/table.go b/table.go
index d26f8fd..c5a704c 100644
--- a/table.go
+++ b/table.go
@@ -77,8 +77,7 @@ func (f *File) AddTable(sheet, hcell, vcell, format string) error {
 	sheetRelationshipsTableXML := "../tables/table" + strconv.Itoa(tableID) + ".xml"
 	tableXML := strings.Replace(sheetRelationshipsTableXML, "..", "xl", -1)
 	// Add first table for given sheet.
-	sheetPath, _ := f.sheetMap[trimSheetName(sheet)]
-	sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(sheetPath, "xl/worksheets/") + ".rels"
+	sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(f.sheetMap[trimSheetName(sheet)], "xl/worksheets/") + ".rels"
 	rID := f.addRels(sheetRels, SourceRelationshipTable, sheetRelationshipsTableXML, "")
 	f.addSheetTable(sheet, rID)
 	err = f.addTable(sheet, tableXML, hcol, hrow, vcol, vrow, tableID, formatSet)
diff --git a/xmlChart.go b/xmlChart.go
index a02da2a..84c1a3b 100644
--- a/xmlChart.go
+++ b/xmlChart.go
@@ -141,25 +141,25 @@ type aSchemeClr struct {
 // attrValInt directly maps the val element with integer data type as an
 // attribute。
 type attrValInt struct {
-	Val int `xml:"val,attr"`
+	Val *int `xml:"val,attr"`
 }
 
 // attrValFloat directly maps the val element with float64 data type as an
 // attribute。
 type attrValFloat struct {
-	Val float64 `xml:"val,attr"`
+	Val *float64 `xml:"val,attr"`
 }
 
 // attrValBool directly maps the val element with boolean data type as an
 // attribute。
 type attrValBool struct {
-	Val bool `xml:"val,attr"`
+	Val *bool `xml:"val,attr"`
 }
 
 // attrValString directly maps the val element with string data type as an
 // attribute。
 type attrValString struct {
-	Val string `xml:"val,attr"`
+	Val *string `xml:"val,attr"`
 }
 
 // aCs directly maps the a:cs element.
diff --git a/xmlPivotTable.go b/xmlPivotTable.go
index 0549c5e..6e1dfb8 100644
--- a/xmlPivotTable.go
+++ b/xmlPivotTable.go
@@ -187,7 +187,7 @@ type xlsxItem struct {
 	F  bool   `xml:"f,attr,omitempty"`
 	M  bool   `xml:"m,attr,omitempty"`
 	C  bool   `xml:"c,attr,omitempty"`
-	X  int    `xml:"x,attr,omitempty,omitempty"`
+	X  int    `xml:"x,attr,omitempty"`
 	D  bool   `xml:"d,attr,omitempty"`
 	E  bool   `xml:"e,attr,omitempty"`
 }
diff --git a/xmlWorksheet.go b/xmlWorksheet.go
index 8f39adf..57fd43f 100644
--- a/xmlWorksheet.go
+++ b/xmlWorksheet.go
@@ -27,7 +27,7 @@ type xlsxWorksheet struct {
 	ProtectedRanges       *xlsxInnerXML                `xml:"protectedRanges"`
 	Scenarios             *xlsxInnerXML                `xml:"scenarios"`
 	AutoFilter            *xlsxAutoFilter              `xml:"autoFilter"`
-	SortState             *xlsxInnerXML                `xml:"sortState"`
+	SortState             *xlsxSortState               `xml:"sortState"`
 	DataConsolidate       *xlsxInnerXML                `xml:"dataConsolidate"`
 	CustomSheetViews      *xlsxCustomSheetViews        `xml:"customSheetViews"`
 	MergeCells            *xlsxMergeCells              `xml:"mergeCells"`
@@ -47,7 +47,7 @@ type xlsxWorksheet struct {
 	SmartTags             *xlsxInnerXML                `xml:"smartTags"`
 	Drawing               *xlsxDrawing                 `xml:"drawing"`
 	LegacyDrawing         *xlsxLegacyDrawing           `xml:"legacyDrawing"`
-	LegacyDrawingHF       *xlsxInnerXML                `xml:"legacyDrawingHF"`
+	LegacyDrawingHF       *xlsxLegacyDrawingHF         `xml:"legacyDrawingHF"`
 	DrawingHF             *xlsxDrawingHF               `xml:"drawingHF"`
 	Picture               *xlsxPicture                 `xml:"picture"`
 	OleObjects            *xlsxInnerXML                `xml:"oleObjects"`
@@ -328,6 +328,16 @@ type xlsxRow struct {
 	C            []xlsxC `xml:"c"`
 }
 
+// xlsxSortState directly maps the sortState element. This collection
+// preserves the AutoFilter sort state.
+type xlsxSortState struct {
+	ColumnSort    bool   `xml:"columnSort,attr,omitempty"`
+	CaseSensitive bool   `xml:"caseSensitive,attr,omitempty"`
+	SortMethod    string `xml:"sortMethod,attr,omitempty"`
+	Ref           string `xml:"ref,attr"`
+	Content       string `xml:",innerxml"`
+}
+
 // xlsxCustomSheetViews directly maps the customSheetViews element. This is a
 // collection of custom sheet views.
 type xlsxCustomSheetViews struct {
@@ -424,7 +434,7 @@ type DataValidation struct {
 	ShowErrorMessage bool    `xml:"showErrorMessage,attr,omitempty"`
 	ShowInputMessage bool    `xml:"showInputMessage,attr,omitempty"`
 	Sqref            string  `xml:"sqref,attr"`
-	Type             string  `xml:"type,attr"`
+	Type             string  `xml:"type,attr,omitempty"`
 	Formula1         string  `xml:",innerxml"`
 	Formula2         string  `xml:",innerxml"`
 }
@@ -448,7 +458,7 @@ type DataValidation struct {
 type xlsxC struct {
 	XMLName  xml.Name `xml:"c"`
 	XMLSpace xml.Attr `xml:"space,attr,omitempty"`
-	R        string   `xml:"r,attr"`           // Cell ID, e.g. A1
+	R        string   `xml:"r,attr,omitempty"` // Cell ID, e.g. A1
 	S        int      `xml:"s,attr,omitempty"` // Style reference.
 	// Str string `xml:"str,attr,omitempty"` // Style reference.
 	T  string  `xml:"t,attr,omitempty"` // Type.
@@ -665,6 +675,14 @@ type xlsxLegacyDrawing struct {
 	RID     string   `xml:"http://schemas.openxmlformats.org/officeDocument/2006/relationships id,attr,omitempty"`
 }
 
+// xlsxLegacyDrawingHF specifies the explicit relationship to the part
+// containing the VML defining pictures rendered in the header / footer of the
+// sheet.
+type xlsxLegacyDrawingHF struct {
+	XMLName xml.Name `xml:"legacyDrawingHF"`
+	RID     string   `xml:"http://schemas.openxmlformats.org/officeDocument/2006/relationships id,attr,omitempty"`
+}
+
 type xlsxInnerXML struct {
 	Content string `xml:",innerxml"`
 }