EXFO FTB-700 for FTB-1 - Manual (Page 235)

Analyzing Traces with the Bidirectional Analysis Application (Optional)
OTDR 227
Inserting Events
5. Specify the exact location where you want to insert an event.
Four markers are available to help you place the event, but only
marker A identifies where the event will be inserted. Define the new
event location by using one of the following methods:

Enter a distance value in the Position box, and press .

Move the markers on the trace display. For more information on
positioning markers, see Using Markers to Edit Events on page 223.
Marker a
Marker A Marker B
Marker b