...
Plugins are executed after the core step has completed, or if the step is considered Optional. When a Plugin is executed, handoff is via a URL. More details about this are in the Plugin Documentation. Because Plugins must be run one at a time, a specific ordering is defined in order to ensure predictability. For Registry v3.3.x and earlier, Plugins are executed alphabetically to ensure a predictable order. However, this order is subject to change in a future release. For Registry v4.0.0 and later, Plugins are executed in the order defined in the Enrollment Flow Wedge configuration for the relevant Enrollment Flow. Once all Plugins have been run, the next step will be initiated.
...