A timestamp is an index-value pair. The index represents the point in the event processing chain at which the timestamp was recorded, for example upstream entry to semantic mapper and the value is a floating point number representing the time. The TimestampSet class defines a set of standard indexes but a custom plug-in can define additional indexes for even finer-grained measurements. When you add a custom index definition, be sure to preserve the correct order, for example, an index denoting an entry point should be less than an one denoting an exit point from that component.

Timestamps are relative measurements and are meant to be compared only to other timestamps in the same or similar processes on the same computer.