If a branch has multiple Code Reviews there is no way for the Before and After EditReview trigger to identify which code review is actually being edited. The current environment variables provide the new values and there is no way to determine what the old values were.
This is important because (for example) we want to only allow certain users from changing the Review Status from Pending to Approved. Therefore we need to find the existing values for the review being edited.

The suggestion is to add an environment variable (PLASTICREVIEWID) for the review ID being edited.