EXFO OTDR 2 - Manual (Page 203)

Description of Event Types
OTDR 195
Merged Event

The total loss ( dB) produced by the events is measured by plotting
two straight lines.

The first line is plotted by fitting, through least-square
approximation, trace points in the linear area preceding the first
event.

The second line is plotted by fitting, through least-square
approximation, trace points in the linear area following the second
event. If there were more than two merged events, this line would
be plotted in the linear area following the last merged event. This
line is then projected toward the first merged event.

The total loss ( dB) equals the power difference between the
point where the first event begins (point A) and the point on the
projected straight line located just below the first event (point B).

No loss value can be specified for the subevents.