ECOs admit that no design is ever completely perfect, infallible. They are neither a positive or negative event, ECOs are an eventuality. The cause could be: a design error evident only during the testing phases of the product; change in customer needs, market demands, and/or governmental regulations or policies; manufacturer problems such as not enough material and/or material specification changes according to changes in the design. All previous post did a good job of outlining the ECO process as well as the information they contain. Overall, ECOs produce instruction because they identify the change, characterize the change, list those affected by the change, reason the change, and determine when the change should be implemented. Instructions are important because they establish control and direction over any obstacles the team might face during project/product development.