2.2.3.5 Axis Group

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An axis group is a set of axes (section 2.2.3.6) that specify a coordinate system, a set of chart groups (section 2.2.3.7) that are plotted using these axes and the plot area that defines where the axes are rendered on the chart (section 2.2.3.3).

An axis group is specified by a sequence of records that conforms to the AXISPARENT rule (section 2.1.7.20.1) specified by the chart sheet substream (section 2.1.7.20.1) ABNF.

The following records and rules define the significant parts of an axis group:

  • The AxisParent record (section 2.4.13) specifies if the axis group is the primary axis group or the secondary axis group on a chart. Often the axes of the primary axis group are displayed to the left and bottom sides of the plot area, while axes of the secondary axis group are displayed on the right and top sides of the plot area.

  • The Pos record (section 2.4.201) specifies the position and size of the outer plot area. The outer plot area is the bounding rectangle that includes the axis labels, the axis titles, and data table (section 2.2.3.14) of the chart. This record MUST be ignored on a secondary axis group.

  • The sequences of records that conform to the IVAXIS (section 2.1.7.20.1), DVAXIS (section 2.1.7.20.1), and SERIESAXIS (section 2.1.7.20.1) rules in the collection of records that conform to the AXES rule (section 2.1.7.20.1) specify the axes of the axis group.

  • The sequences of records that conform to the ATTACHEDLABEL rule (section 2.1.7.20.1) in the sequence of records that conform to the AXES rule specify the axis titles of the axis group. Each attached label (section 2.2.3.15) MUST contain an ObjectLink record (section 2.4.182) that conforms to the following requirements:

    • The wLinkObj field MUST equal to 0x0002, 0x0003, or 0x0007, indicating which axis the axis title is associated.

    • The wLinkObj field MUST specify an axis defined in the current axis group.

    • The wLinkObj field MUST be unique among the other attached labels that represent axis titles in the same axis group.

  • The PlotArea record (section 2.4.197) and the sequence of records that conforms to the FRAME rule (section 2.1.7.20.1) in the sequence of records that conform to the AXES rule specify the properties of the inner plot area. The inner plot area is the rectangle bounded by the chart axes. The PlotArea record (section 2.4.197) MUST NOT exist on a secondary axis group.

  • The sequences of records that conform to the CRT rule (section 2.1.7.20.1) specify the chart groups of the axis group.

Because there are many different ways to represent data visually, each representation has specific requirements about the layout of the data and the way it is plotted. This results in restrictions on the combinations of chart group types that can be plotted on the same axis group, and the combinations of chart group types that can be plotted in the same chart.

A chart MUST contain one of the following:

  • A single axis group that contains a single chart group that contains a Chart3d record (section 2.4.46).

  • One or two axis groups that each contain a single bubble chart group.

  • One or two axis groups that each conform to one of the following restrictions on chart group type combinations:

    • Zero or one of each of the following chart group types: area, column, line, and scatter.

    • Zero or one of each of the following chart group types: bar of pie, doughnut, pie, and pie of pie.

    • A single bar chart group.

    • A single filled radar chart group.

    • A single radar chart group.

In addition to the restrictions on the combinations of chart group types that can be plotted on the same axis group or chart, there are additional restrictions on the axes of the axis group based on the chart groups of the axis group.

The following restrictions apply to the axes of an axis group:

  • The axis group MUST NOT contain any axes if the axis group contains a bar of pie, doughnut, pie, or pie of pie chart group.

  • The axis group MUST contain a category (2) or date axis if the axis group contains an area, bar, column, filled radar, line, radar, or surface chart group.

  • The axis group MUST contain an area, bar, column, filled radar, line, radar, or surface chart group if the axis group contains a category (2) or date axis.

  • The axis group MUST contain two value axes if and only if all chart groups are of type bubble or scatter.

  • The axis group MUST contain a series axis if and only if the chart group attached to the axis group is one of the following:

    • An area chart group with the fStacked field of the Area record (section 2.4.2) equal to 0.

    • A column chart group with the fStacked field of the Bar record (section 2.4.15) equal to 0 and the fCluster field of the Chart3d record equal to 0.

    • A line chart group with field fStacked of the Line record (section 2.4.155) equal to 0.

    • A surface chart group.

  • The chart group on the axis group MUST contain a Chart3d record if the axis group contains a series axis.