Sorry, should clarify. By difference in fare, I mean a change actually requiring the difference in fare to be collected due to the policy it was initiated under. Most cases this is going to be a voluntarily requested change, agents have no empowerment to choose to waive an add-collect for a voluntary change. The IRROPs (and schedule change) policy specifically calls out that no add-collect is necessary if rebooked within the guidelines of the policy, even though it often requires a different booking code. So empowerment isn't necessary in an IRROPs situation, having the experience to know how to override the system to process the change without it trying to charge the add collect is.