Adds a defined set of systems to a specified static group or removes a defined set of systems from the specified static group. Use this event action to initialize a set of systems to process. Then the processing is triggered by an event that you specify in your event filter.
For example, create a static group that contains all the systems that require updating. After each system is updated, an event is generated. That event can trigger this event action to remove the updated system from the static group. When there are no more systems in the static group, you know all systems have been updated.