EXFO OTDR 2 - Manual (Page 193)

OTDR 185
B Description of Event Types
This section describes all types of events that may appear in the events
table generated by the application. Here is a guide to the descriptions:

Each type of event has its own symbol.

Each type of event is represented by a graph of a fiber trace, which
illustrates the power reflected back toward the source as a function of
distance.

An arrow points to the location of the event type in the trace.

Most graphs show one complete trace; that is, an entire acquisition
range.

Some graphs show only a portion of the entire range to view events of
interest more closely.