A Commit Action rule is defined by a method with the @CommitAction annotation:
This annotation has only one (optional) parameter
A Commit Action is invoked any time an object is touched (inserted, modified or deleted), but, unlike an Action, it is only invoked once, at the very end of the transaction processing.
As a result, a Commit Action is not allowed to modify any persistent data (at least nothing that might activate additional business logic).
The name of the method does not matter, but the method must be declared