EXFO FTB-7000 OTDR Series for FTB-500 - Manual (Page 118)

Testing Fibers in Template Mode
104 OTDR
Acquiring Traces in Template Mode
5. Question marks will appear in the Event table to identify new events
not found on the reference trace. If you want to add these marked
events to the reference trace, press Add to Ref. You can also delete
unwanted events with the Delete button.
³
Asterisks (“*”) identify events that were not found on the main trace,
but that were added because they exist on the reference trace.
³
Question marks identify events found on the main trace that do not
exist on the reference trace. Numbers will be assigned to new events
when the trace is analyzed.
Asterisks and question marks are used to identify events without
modifying the existing event numbers. This way, you can match the
events of the reference trace with those of the main trace more easily.
Note: If you select the Analyze reference events only feature (from Setup), the
Add to Ref. and Delete buttons are unavailable. Events that are not on the
reference trace, but that are detected on the acquired trace, are deleted.