Use the SetSampleRowHeaderString method to customize the row heads for the sample data
this.InitSPCTimeVariableControlChart(charttype, numsamplespersubgroup, numdatapointsinview, timeincrementminutes);
this.ChartData.SetSampleRowHeaderString(0, "Sample #1");
this.ChartData.SetSampleRowHeaderString(1, "Sample #2");
this.ChartData.SetSampleRowHeaderString(2, "Sample #3");
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