EXFO FTB-700 for FTB-1 - Manual (Page 205)

Analyzing Traces with the Bidirectional Analysis Application (Optional)
OTDR 197
Creating Bidirectional Measurement Files
When two traces are opened in the bidirectional analysis application, the
span end of the B->A trace is aligned with the span start of the A->B trace.
If the application cannot match the traces perfectly, error or warning
messages will appear. A message will be displayed if there are
inconsistencies in the events table, wavelength, index of refraction, helix
factor, or Rayleigh backscatter coefficient.
Note: The A->B and B->A traces are displayed in full view mode (1:1 zoom
factor).