similarEvent

Accepts events that are similar to one in the included event source.

Example 

<similarEvent>
  <fdsnEvent>
      <originTimeRange>
          <startTime>
              2015-01-01T00:00:00.000Z
          </startTime>
          <endTime>
              2015-01-31T23:59:59.999Z
          </endTime>
      </originTimeRange>
      <magnitudeRange>
          <min>6.0</min>
      </magnitudeRange>
  </fdsnEvent>
</similarEvent>

This consists of

Places this can be found

In origin there is a choice between all of the following