This is a measurement that aggregates several - potentially many - measurements in a single object. It is intended for situations that have interesting details but do not warrant full-blown child measurements.
A typical example of this is iterating over a JDBC ResultSet: calling 'next()' on the ResultSet may take significant time, and measuring that time can be of interest. It is however often sufficient to measure the total time used up by iterating over the ResultSet.
@author arno