Void an already completed transaction. For example, suppose that you, as the initiator, successfully execute a Chem eStandards E41 transaction with one of your trading partners. The conversation ends when your trading partner receives the final Receipt ACK successfully from you, indicating that you have received their Purchase Order Response. However, after the conversation ends, you encounter a semantic error in their PO Response (for example, the PO Response states that you ordered four PCs instead of only two, as you stated in your PO Request).

Cancel a transaction in progress. For example, suppose that you, as the seller, have received a Chem eStandards E41 PO Request from your trading partner and have sent a Receipt ACK. While processing the PO in your back‐end, you realize that you have a semantic problem with the PO received.