Test description contains two elements - info-collectors and scenario.
Info-collectors is a list of collectors. Collector can be as metric element or as validator element.
In scenario you can describe what targets will be loaded and what tool use to make load.
You can turn on calibration by adding attribute calibration="true".
Calibration is a process, when Jagger in a simple(one thread) mode load every target only one time.
The results, that were calculated in this process, will be a benchmark for comparison with the new iterations.