What are different stages used in Plug-In registration?

Event	Stage name	Stage number	Description
Pre-Event	Pre-validation	10	Stage in the pipeline for plug-ins that are to execute before the main system operation. Plug-ins registered in this stage may execute outside the database transaction. Security Note The pre-validation stage occurs prior to security checks being performed to verify the calling or logged on user has the correct permissions to perform the intended operation.
Pre-Event	Pre-operation	20	Stage in the pipeline for plug-ins that are to execute before the main system operation. Plug-ins registered in this stage are executed within the database transaction.
Platform Core Operation	MainOperation	30	In-transaction main operation of the system, such as create, update, delete, and so on. No custom plug-ins can be registered in this stage. For internal use only.
Post-Event	Post-operation	40	Stage in the pipeline for plug-ins which are to execute after the main operation. Plug-ins registered in this stage are executed within the database transaction.