Description
These functions set or return the frequency of the markers plotted for a specific data set.
A positive value of marker frequency means to plot every "freq" data points. Thus, a value of 10 would mean plot a marker every 10 data points. To mark every data point, set freq to 1. To mark no data points, set freq to 0 (or set the marker type to none.)
A negative value of marker frequency means plot a total of "freq" markers. Thus, a value of -10 would mean plot a total of 10 markers.
The data ID is that returned by AddData or SetData.