The Simulation Tool was originally developed as part of SBW. It not only provides a easy to use interface for RoadRunner, even third party simulators have been enabled to run with it, and thus COPASI can be used from it just as well as the SBML ODE Solver (though to be fair, some of the advanced features are only provided by RoadRunner.

What has all that to do with SED-ML? Since the Simulation Tool has been opened up, to provide a plug-in API, one such plug-in provides support for the use of SED-ML. Currently, it just runs the SED-ML simulation experiment. Additionally, all models (or rather all SBML models) encoded within the SED-ML file, can be further analyzed with the remaining simulation experiments: time course simulation, steady state analysis, pulse experiments, (steady state) parameter scans and more.