The first event in a particle flow is always a global event, whose contents affect all particles in the flow; the rest are local events. Although a global event has the same name as the Particle Flow source icon, selecting the source icon in a viewport doesn't highlight the global event, nor does highlighting a global event select the corresponding source icon.
Global event (highlighted)
By default, the global event contains a single Render operator that specifies rendering properties for all particles in the flow. You can add other operators here to have them act globally, such as Material, Display, and Speed.
Note: A global event is the only event that can be wired to another event without using a test. It's almost always wired directly to a birth event.
Attention: When you use an operator globally, be sure not to use the same operator locally (that is, in any other events in the system) to avoid potential conflicts.