EXFO FTB-7000 OTDR Series for FTB-500 - Manual (Page 117)

Testing Fibers in Template Mode
OTDR 103
Acquiring Traces in Template Mode
4. If applicable, the application will display the number of new events
detected for each wavelength.
4a. Press OK to close the dialog box.
Note: You can only add events to the reference trace during reference update.
Note: If you chose the Keep all newly detected events feature for the
acquisitions that will be performed after the update, you may find it useful
to add newly detected events to obtain a more accurate reference trace.