The XmlTkPerspectiveFrt structure specifies the angle of the field of view for the plot area. This structure MUST exist only for bar chart groups and pie chart groups, and MUST exist only when the chart contains a Chart2.4.46d record and the fPerspective field of the Chart2.4.46d record equal to 1. When the angle of the field of view is the default angle, 20, this structure MUST NOT be present.
perspectiveAngle (8 bytes): An XmlTkDWord that specifies the angle of the field of view. The perspectiveAngle.xtHeader.xmlTkTag field MUST be 0x004D. The value of perspectiveAngle.dValue field MUST equal to two times the view angle and MUST be greater than or equal to 0 and less than or equal to 200. This field overrides the pcDist field of the Chart2.4.46d record in the chart sheet substream.