Controls which dimension is used to sort the items in the collection (when Sorted is True).
A chart value, depending on the chart type, can contain 1 or more dimensional values that define the chart value. For example, each chart value in a bar chart contains 1 value (defining the height of the bar), line chart values contains 2 dimensions: X and Y, and shape chart values contain 4 dimensions: X, Y, Width, and Height. The SortByDimension allows you to sort the items by the dimension (X usually but it could be Width in a shape chart, Level in a graph chart, etc). See the
ValueCount properties of the TRSChartValue item for more information.