How is time point "T-end" determined by the ECG Analysis Module?

For a non-rodent ECG, the ECG Analysis Module estimates the T-end by first finding the T-wave peak time point (T-peak). Following the peak, a least squares fitted line is drawn from 70% to 30% amplitude on the falling slope following the peak. T-End is then marked as the intersection of the fitted line and the isoelectric level of the waveform. It is  not the intersection of the isoelectric line and the ECG signal itself. 

The rodent T-end uses a simple intersection of the ECG signal itself with the isoelectric line. 

The LabChart Help menu has a section describing these algorithms on the page "ECG Averaging" under the subsection "Calculations" which is at the bottom of the page.