ElementType:
| "chartArea"
| "title"
| "legend"
| "legendEntry"
| "plotArea"
| "dataTable"
| "axis"
| "axisTitle"
| "gridlines"
| "series"
| "point"
| "marker"
| "dataLabels"
| "dataLabel"
| "trendline"
| "trendlineLabel"
| "errorBars"
| "chartGroup"
| "upDownBars"
| "hiLoLines"
| "dropLines"
| "seriesLines"
What an element of a chart is: see IChart.IElement.getElementType.